{"id":9379,"date":"2020-04-16T22:44:12","date_gmt":"2020-04-16T14:44:12","guid":{"rendered":"https:\/\/www.zhangxinxu.com\/wordpress\/?p=9379"},"modified":"2020-04-16T22:46:11","modified_gmt":"2020-04-16T14:46:11","slug":"es6-math-number","status":"publish","type":"post","link":"https:\/\/www.zhangxinxu.com\/wordpress\/2020\/04\/es6-math-number\/","title":{"rendered":"ES6 Math\u65b9\u6cd5\u548cNumber\u65b0\u7279\u6027\u7b80\u4ecb"},"content":{"rendered":"<p>by <a href=\"https:\/\/www.zhangxinxu.com\/\">zhangxinxu<\/a> from <a href=\"https:\/\/www.zhangxinxu.com\/wordpress\/?p=9379\">https:\/\/www.zhangxinxu.com\/wordpress\/?p=9379<\/a><br \/>\n\u672c\u6587\u6b22\u8fce\u5206\u4eab\u4e0e\u805a\u5408\uff0c\u5168\u6587\u8f6c\u8f7d\u5c31\u4e0d\u5fc5\u4e86\uff0c\u5c0a\u91cd\u7248\u6743\uff0c\u5708\u5b50\u5c31\u8fd9\u4e48\u5927\uff0c\u82e5\u6025\u7528\u53ef\u4ee5\u8054\u7cfb\u6388\u6743\u3002<\/p>\n<p><script>window.wxShareImgUrl = 'https:\/\/www.zhangxinxu.com\/study\/image\/share\/202004-love.png';<\/script><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/\/image.zhangxinxu.com\/image\/blog\/202004\/nice-cover.png\" width=\"383\" height=\"255\" alt=\"\u4e0d\u9519\u7684\u60c5\u4fa3\u5c01\u9762\u56fe\" class=\"alignnone clip thumb size-medium\" \/><\/p>\n<h3>\u4e00\u3001ES6\u4e2d\u7684Math\u5bf9\u8c61<\/h3>\n<p>\u5168\u5c40\u5bf9\u8c61Math\u5728ES6\u4e2d\u65b0\u589e\u4e86\u51e0\u4e2a\u65b9\u6cd5\u3002<\/p>\n<p>\u9996\u5148\u6765\u770b\u4e0b\u5404\u79cd\u6570\u503c\u529f\u80fd\u65b9\u6cd5\u3002<\/p>\n<h4>Math.sign(x)<\/h4>\n<p><code>Math.sign()<\/code>\u51fd\u6570\u8fd4\u56de\u4e00\u4e2a\u6570\u5b57\u7684\u7b26\u53f7, \u6307\u793a\u6570\u5b57\u662f\u6b63\u6570\uff0c\u8d1f\u6570\u8fd8\u662f\u96f6\u3002<\/p>\n<p>\u6b64\u51fd\u6570\u5171\u67095\u79cd\u8fd4\u56de\u503c, \u5206\u522b\u662f 1, -1, 0, -0, NaN. \u4ee3\u8868\u7684\u5206\u522b\u662f\u6b63\u6570, \u8d1f\u6570, \u6b63\u96f6, \u8d1f\u96f6, NaN\u3002<\/p>\n<p>\u4f20\u5165\u8be5\u51fd\u6570\u7684\u53c2\u6570\u4f1a\u88ab\u9690\u5f0f\u8f6c\u6362\u6210\u6570\u5b57\u7c7b\u578b\u3002<\/p>\n<p>\u4f8b\u5982\uff1a<\/p>\n<pre>Math.sign(3);         <span style=\"color:green;\">\/\/  1<\/span>\r\nMath.sign(-3);        <span style=\"color:green;\">\/\/ -1<\/span>\r\nMath.sign(\"-3\");      <span style=\"color:green;\">\/\/ -1<\/span>\r\nMath.sign(0);         <span style=\"color:green;\">\/\/  0<\/span>\r\nMath.sign(-0);        <span style=\"color:green;\">\/\/ -0<\/span>\r\nMath.sign(-Infinity); <span style=\"color:green;\">\/\/ -1<\/span>\r\nMath.sign(Infinity);  <span style=\"color:green;\">\/\/  1<\/span>\r\nMath.sign(NaN);       <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.sign(\"foo\");     <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.sign();          <span style=\"color:green;\">\/\/ NaN<\/span><\/pre>\n<p>\u5bf9\u4e8e\u4e0d\u652f\u6301\u7684\u6d4f\u89c8\u5668\u53ef\u4ee5\u4f7f\u7528\u4e0b\u9762\u7684Polyfill\uff1a<\/p>\n<pre>if (!Math.sign) {\r\n  Math.sign = function(x) {\r\n    <span style=\"color:green;\">\/\/ \u5982\u679c x \u662f NaN, \u7ed3\u679c\u662f NaN.\r\n    \/\/ \u5982\u679c x \u662f -0\uff0c\u7ed3\u679c\u662f -0.\r\n    \/\/ \u5982\u679c x \u662f +0\uff0c\u7ed3\u679c\u662f +0.\r\n    \/\/ \u5982\u679c x \u662f \u8d1f\u6570\u4f46\u4e0d\u662f -0\uff0c\u7ed3\u679c\u662f -1.\r\n    \/\/ \u5982\u679c x \u662f \u6b63\u6570\u4f46\u4e0d\u662f +0\uff0c\u7ed3\u679c\u662f +1.<\/span>\r\n    x = +x; <span style=\"color:green;\">\/\/ \u8f6c\u6362\u6210\u6570\u503c<\/span>\r\n    if (x === 0 || isNaN(x)) {\r\n      return Number(x);\r\n    }\r\n    return x > 0 ? 1 : -1;\r\n  };\r\n}<\/pre>\n<h4>Math.trunc(x)<\/h4>\n<p>\u5355\u8bcdtrunc\u662f\u622a\u65ad\u622a\u53d6\u7684\u610f\u601d\uff0c<code>Math.trunc()<\/code>\u65b9\u6cd5\u4f1a\u5c06\u6570\u5b57\u7684\u5c0f\u6570\u90e8\u5206\u53bb\u6389\uff0c\u53ea\u4fdd\u7559\u6574\u6570\u90e8\u5206\u3002<\/p>\n<p>\u4e0d\u50cf Math \u7684\u5176\u4ed6\u4e09\u4e2a\u65b9\u6cd5\uff1a <code>Math.floor()<\/code>\u3001<code>Math.ceil()<\/code>\u3001<code>Math.round()<\/code> \uff0c<code>Math.trunc()<\/code>\u7684\u6267\u884c\u903b\u8f91\u5f88\u7b80\u5355\uff0c\u4ec5\u4ec5\u662f\u5220\u9664\u6389\u6570\u5b57\u7684\u5c0f\u6570\u90e8\u5206\u548c\u5c0f\u6570\u70b9\uff0c\u4e0d\u7ba1\u53c2\u6570\u662f\u6b63\u6570\u8fd8\u662f\u8d1f\u6570\u3002<\/p>\n<p>\u4f20\u5165\u8be5\u65b9\u6cd5\u7684\u53c2\u6570\u4f1a\u88ab\u9690\u5f0f\u8f6c\u6362\u6210\u6570\u5b57\u7c7b\u578b\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.trunc(13.37)    <span style=\"color:green;\">\/\/ 13<\/span>\r\nMath.trunc(42.84)    <span style=\"color:green;\">\/\/ 42<\/span>\r\nMath.trunc(0.123)    <span style=\"color:green;\">\/\/  0<\/span>\r\nMath.trunc(-0.123)   <span style=\"color:green;\">\/\/ -0<\/span>\r\nMath.trunc(\"-1.123\") <span style=\"color:green;\">\/\/ -1<\/span>\r\nMath.trunc(NaN)      <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.trunc(\"foo\")    <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.trunc()         <span style=\"color:green;\">\/\/ NaN<\/span><\/pre>\n<p>\u5982\u679c\u60f3\u8981\u5728IE\u6d4f\u89c8\u5668\u4e2d\u4f7f\u7528\uff0c\u53ef\u4ee5\u8bd5\u8bd5\u4e0b\u9762\u7684Polyfill\u4ee3\u7801\uff1a<\/p>\n<pre>if (!Math.trunc) {\r\n  Math.trunc = function(v) {\r\n    v = +v;\r\n    return (v - v % 1) || (!isFinite(v) || v === 0 ? v : v < 0 ? -0 : 0);\r\n  };\r\n}<\/pre>\n<h4>Math.cbrt(x)<\/h4>\n<p><code>Math.cbrt()<\/code>\u51fd\u6570\u8fd4\u56de\u4efb\u610f\u6570\u5b57\u7684\u7acb\u65b9\u6839\u3002<\/p>\n<p>\u4f8b\u5982\uff1a<\/p>\n<pre>Math.cbrt(8); <span style=\"color:green;\">\/\/ 2<\/span>\r\nMath.cbrt(NaN); <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.cbrt(-1); <span style=\"color:green;\">\/\/ -1<\/span>\r\nMath.cbrt(-0); <span style=\"color:green;\">\/\/ -0<\/span>\r\nMath.cbrt(-Infinity); <span style=\"color:green;\">\/\/ -Infinity<\/span>\r\nMath.cbrt(0); <span style=\"color:green;\">\/\/ 0<\/span>\r\nMath.cbrt(1); <span style=\"color:green;\">\/\/ 1<\/span>\r\nMath.cbrt(Infinity); <span style=\"color:green;\">\/\/ Infinity<\/span>\r\nMath.cbrt(null); <span style=\"color:green;\">\/\/ 0<\/span>\r\nMath.cbrt(2);  <span style=\"color:green;\">\/\/ 1.2599210498948734<\/span><\/pre>\n<p>Polyfill\u4ee3\u7801\u5982\u4e0b\uff0c\u53ef\u4ee5\u517c\u5bb9\u8001\u65e7\u7684\u6d4f\u89c8\u5668\uff1a<\/p>\n<pre>if (!Math.cbrt) {\r\n  Math.cbrt = function(x) {\r\n    var y = Math.pow(Math.abs(x), 1\/3);\r\n    return x < 0 ? -y : y;\r\n  };\r\n}<\/pre>\n<h4>Math.expm1(x)<\/h4>\n<p><code>Math.expm1()<\/code> \u51fd\u6570\u8fd4\u56de Ex - 1\uff0c\u5176\u4e2d x \u662f\u8be5\u51fd\u6570\u7684\u53c2\u6570, E \u662f\u81ea\u7136\u5bf9\u6570\u7684\u5e95\u6570 2.718281828459045\u3002<\/p>\n<p><code>Math.expm1()<\/code>\u4e2d\u7684expm1 \u662f \"exponent minus 1\" \u7684\u7f29\u5199\uff0c\u8bed\u4e49\u4e0a\u7b49\u540c\u4e8eMath.exp(x)-1\uff0c\u4f46\u662f\u5b9e\u9645\u4e0a\u4e24\u8005\u8fd8\u662f\u6709\u533a\u522b\u7684\uff0c\u5f53Math.exp()\u7684\u7ed3\u679c\u63a5\u8fd1\u4e8e1\u7684\u65f6\u5019\uff0cMath.expm1()\u7684\u7cbe\u5ea6\u66f4\u9ad8\uff0c\u4f8b\u5982\uff1a<\/p>\n<pre>Math.expm1(1e-10);\r\n<span style=\"color:green;\">\/\/ 1.00000000005e-10<\/span>\r\nMath.exp(1e-10) - 1;\r\n<span style=\"color:green;\">\/\/ 1.000000082740371e-10<\/span><\/pre>\n<p>\u8bed\u6cd5\uff1a<\/p>\n<pre>Math.expm1(x)<\/pre>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.expm1(-1); <span style=\"color:green;\">\/\/ -0.6321205588285577<\/span>\r\nMath.expm1(0);  <span style=\"color:green;\">\/\/ 0<\/span>\r\nMath.expm1(1)     <span style=\"color:green;\">\/\/ 1.7182818284590453<\/span>\r\nMath.expm1(-38)   <span style=\"color:green;\">\/\/ -1<\/span>\r\nMath.expm1(\"-38\") <span style=\"color:green;\">\/\/ -1<\/span>\r\nMath.expm1(\"foo\") <span style=\"color:green;\">\/\/ NaN<\/span><\/pre>\n<p>Polyfill\u4ee3\u7801\u5982\u4e0b\uff0c\u53ef\u4ee5\u517c\u5bb9Internet Explorer\u6d4f\u89c8\u5668\uff1a<\/p>\n<pre>Math.expm1 = Math.expm1 || function(x) {\r\n  return Math.exp(x) - 1;\r\n};<\/pre>\n<h4>Math.log1p(x)<\/h4>\n<p><code>Math.log1p()<\/code>\u8fd4\u56de\u53c2\u6570\u503c+1\u7684\u81ea\u7136\u5bf9\u6570\uff08e\uff09\uff0c\u7528\u6570\u5b66\u516c\u5f0f\u8868\u793a\u5c31\u662f\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/image.zhangxinxu.com\/image\/blog\/202004\/2020-04-13_134246.png\" width=\"288\" height=\"28\" alt=\"\"><\/p>\n<p>\u5982\u679c\u53c2\u6570\u503cx\u5c0f\u4e8e-1\uff0c\u5219\u8fd4\u56deNaN\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.log1p(1);  <span style=\"color:green;\">\/\/ 0.6931471805599453<\/span>\r\nMath.log1p(0);  <span style=\"color:green;\">\/\/ 0<\/span>\r\nMath.log1p(-1); <span style=\"color:green;\">\/\/ -Infinity<\/span>\r\nMath.log1p(-2); <span style=\"color:green;\">\/\/ NaN<\/span><\/pre>\n<p>\u5bf9\u4e8e\u975e\u5e38\u5c0f\u7684x\u503c\uff0c\u6dfb\u52a01\u53ef\u4ee5\u964d\u4f4e\u6216\u6d88\u9664\u7cbe\u5ea6\u3002<\/p>\n<p>JS\u4e2d\u4f7f\u7528\u7684\u53cc\u6d6e\u70b9\u6570\u53ef\u4ee5\u63d0\u4f9b\u5927\u7ea615\u4f4d\u7684\u7cbe\u5ea6\u30021+1e-15=1.000000000000001\uff0c\u4f461+1e-16=1.000000000000000\uff0c\u56e0\u6b64\u5728\u8be5\u7b97\u6cd5\u4e2d\u6b63\u597d\u662f1.0\uff0c\u56e0\u4e3a\u8d85\u8fc715\u7684\u6570\u5b57\u662f\u56db\u820d\u4e94\u5165\u7684\u3002<\/p>\n<p>\u5f53\u4f60\u8ba1\u7b97\u5bf9\u6570\uff081+x\uff09\u65f6\uff0c\u5982\u679cx\u5f88\u5c0f\uff0c\u4f60\u5e94\u8be5\u5f97\u5230\u4e00\u4e2a\u975e\u5e38\u63a5\u8fd1x\u7684\u7b54\u6848\uff08\u8fd9\u5c31\u662f\u4e3a\u4ec0\u4e48\u8fd9\u4e9b\u88ab\u79f0\u4e3a\u201c\u81ea\u7136\u201d\u5bf9\u6570\uff09\u3002\u5982\u679c\u4f60\u8ba1\u7b97Math.log\uff081+1.1111111e-15\uff09\uff0c\u4f60\u4f1a\u5f97\u5230\u63a5\u8fd11.1111111e-15\u7684\u7b54\u6848\u3002\u53d6\u800c\u4ee3\u4e4b\u7684\u662f\uff0c\u4f60\u5c06\u5f97\u52301.00000000000000111022\u7684\u5bf9\u6570\uff08\u820d\u5165\u662f\u4e8c\u8fdb\u5236\u7684\uff0c\u6240\u4ee5\u6709\u65f6\u4f1a\u53d8\u5f97\u96be\u770b\uff09\uff0c\u6240\u4ee5\u4f60\u5f97\u5230\u7684\u7b54\u6848\u662f1.11022\u2026e-15\uff0c\u53ea\u67093\u4e2a\u6b63\u786e\u7684\u6570\u5b57\u3002\u76f8\u53cd\uff0c\u5982\u679c\u4f60\u8ba1\u7b97Math.log1p\uff081.1111111e-15\uff09\uff0c\u4f60\u4f1a\u5f97\u5230\u4e00\u4e2a\u66f4\u7cbe\u786e\u7684\u7b54\u68481.1111110999995e-15\uff0c\u7cbe\u786e\u523015\u4f4d\uff08\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\u5b9e\u9645\u4e0a\u662f16\u4f4d\uff09\u3002<\/p>\n<p><code>Math.log1p()<\/code>\u65b9\u6cd5IE\u6d4f\u89c8\u5668\u4e0d\u652f\u6301\uff0cpolyfill\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre>Math.log1p = Math.log1p || function(x) {\r\n  return Math.log(1 + x);\r\n};<\/pre>\n<h4>Math.log2(x)<\/h4>\n<p><code>Math.log2()<\/code>\u65b9\u6cd5\u8fd4\u56de\u4ee52\u4e3a\u5e95\u7684\u5bf9\u6570\u3002<\/p>\n<p>\u516c\u5f0f\u5982\u4e0b\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/image.zhangxinxu.com\/image\/blog\/202004\/2020-04-13_152802.png\" width=\"482\" height=\"33\" alt=\"Math.log2(\u516c\u5f0f)\"><\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.log2(8);    <span style=\"color:green;\">\/\/ 3<\/span>\r\nMath.log2(3);    <span style=\"color:green;\">\/\/ 1.584962500721156<\/span>\r\nMath.log2(2);    <span style=\"color:green;\">\/\/ 1<\/span>\r\nMath.log2(1);    <span style=\"color:green;\">\/\/ 0<\/span>\r\nMath.log2(0);    <span style=\"color:green;\">\/\/ -Infinity<\/span>\r\nMath.log2(-2);   <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.log2(1024); <span style=\"color:green;\">\/\/ 10<\/span><\/pre>\n<p>\u4e0b\u9762\u662fPolyfill\u4ee3\u7801\uff0c\u6b64Polyfill\u6a21\u62dfMath.log2\u51fd\u6570\u3002\u6ce8\u610f\uff0c\u5982\u679c\u4f7f\u7528\u4f4d\u63a9\u7801\uff0c\u5b83\u4f1a\u5728\u67d0\u4e9b\u8f93\u5165\uff08\u59821<<29\uff09\u4e0a\u8fd4\u56de\u4e0d\u7cbe\u786e\u7684\u503c\uff0c\u5e76\u5305\u88c5\u5230Math.round\uff08\uff09\u4e2d\u3002\n\n\n\n<pre>if (!Math.log2) Math.log2 = function(x) {\r\n  return Math.log(x) * Math.LOG2E;\r\n};<\/pre>\n<h4>Math.log10(x)<\/h4>\n<p><code>Math.log10()<\/code>\u65b9\u6cd5\u8fd4\u56de\u4ee510\u4e3a\u5e95\u7684\u5bf9\u6570\u3002<\/p>\n<p>\u516c\u5f0f\u5982\u4e0b\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/image.zhangxinxu.com\/image\/blog\/202004\/2020-04-13_152816.png\" width=\"502\" height=\"34\" alt=\"Math.log10(\u516c\u5f0f)\"><\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.log10(100);    <span style=\"color:green;\">\/\/ 2<\/span>\r\nMath.log10(2);      <span style=\"color:green;\">\/\/ 0.3010299956639812<\/span>\r\nMath.log10(2);      <span style=\"color:green;\">\/\/ 0.3010299956639812<\/span>\r\nMath.log10(1);      <span style=\"color:green;\">\/\/ 0<\/span>\r\nMath.log10(0);      <span style=\"color:green;\">\/\/ -Infinity<\/span>\r\nMath.log10(-2);     <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.log10(100000); <span style=\"color:green;\">\/\/ 5<\/span><\/pre>\n<p>\u53c2\u6570x\u5c0f\u4e8e0\u4f1a\u8fd4\u56deNaN\u3002<\/p>\n<p>IE\u6d4f\u89c8\u5668\u4e0d\u652f\u6301\u8fd9\u4e2aMath\u9759\u6001\u65b9\u6cd5\uff0c\u53ef\u4ee5\u4f7f\u7528\u4e0b\u9762\u7684Polyfill\uff1a<\/p>\n<pre>Math.log10 = Math.log10 || function(x) {\r\n  return Math.log(x) * Math.LOG10E;\r\n};<\/pre>\n<hr>\n<h4>Math.fround(x)<\/h4>\n<p><code>Math.fround()<\/code>\u8fd4\u56de\u6700\u63a5\u8fd1\u768432\u4f4d\u5355\u7cbe\u5ea6\u6d6e\u70b9\u6570\u503c\u3002<\/p>\n<p>\u8bed\u6cd5\uff1a<\/p>\n<pre>var singleFloat = Math.fround(doubleFloat);<\/pre>\n<p>\u5355\u7cbe\u5ea6\u6d6e\u70b9\u6570\u5360\u75284\u4e2a\u5b57\u8282\uff0832\u4f4d\uff09\u5b58\u50a8\u7a7a\u95f4\uff0c\u5305\u62ec\u7b26\u53f7\u4f4d1\u4f4d\uff0c8\u4f4d\u6307\u6570\uff0c23\u4f4d\u5c0f\u6570\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/image.zhangxinxu.com\/image\/blog\/202004\/single-float.jpg\" width=\"590\" height=\"75\" alt=\"\u5355\u7cbe\u5ea6\u6d6e\u70b9\u6570\"><\/p>\n<p>\u800c\u53cc\u7cbe\u5ea6\u662f1\u4f4d\u7b26\u53f7\uff0c11\u4f4d\u6307\u6570\uff0c52\u4f4d\u5c0f\u6570\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/image.zhangxinxu.com\/image\/blog\/202004\/double-float.jpg\" width=\"618\" height=\"128\" alt=\"\u53cc\u7cbe\u5ea6\u6d6e\u70b9\u6570\"><\/p>\n<p>\u5176\u6570\u503c\u8303\u56f4\u4e3a-3.4E38\uff5e3.4E38\uff0c\u5355\u7cbe\u5ea6\u6d6e\u70b9\u6570\u6700\u591a\u67097\u4f4d\u5341\u8fdb\u5236\u6709\u6548\u6570\u5b57\uff0c\u8d85\u51fa\u90e8\u5206\u56db\u820d\u4e94\u5165\u3002\u4e3a\u4ec0\u4e48\u6700\u591a\u662f\u67097\u4f4d\u5462\uff1f\u662f\u8fd9\u6837\u7684\uff0c\u5c0f\u6570\u90e8\u5206\u662f23\u4f4d\uff0c\u9664\u53bb\u5168\u90e8\u4e3a0\u7684\u60c5\u51b5\u4ee5\u5916\uff0c\u6700\u5c0f\u4e3a2\u7684-23\u6b21\u65b9\uff0c\u7ea6\u7b49\u4e8e1.19\u4e58\u4ee510\u7684-7\u6b21\u65b9\uff0c\u6240\u4ee5\u5355\u7cbe\u5ea6\u6d6e\u70b9\u6570\u7684\u5c0f\u6570\u90e8\u5206\u53ea\u80fd\u7cbe\u786e\u5230\u540e\u97626\u4f4d\uff0c\u52a0\u4e0a\u5c0f\u6570\u70b9\u524d\u7684\u4e00\u4f4d\uff0c\u5373\u6709\u6548\u6570\u5b57\u4e3a7\u4f4d\u3002<\/p>\n<p>\u7c7b\u4f3c\uff0cdouble \u5c3e\u6570\u90e8\u520652\u4f4d\uff0c\u6700\u5c0f\u4e3a2\u7684-52\u6b21\u65b9\uff0c\u7ea6\u4e3a2.22\u4e58\u4ee510\u7684-16\u6b21\u65b9\uff0c\u6240\u4ee5\u7cbe\u786e\u5230\u5c0f\u6570\u70b9\u540e15\u4f4d\uff0c\u6709\u6548\u4f4d\u6570\u4e3a16\u4f4d\u3002<\/p>\n<p>\u56de\u5230\u8fd9\u91cc\uff0c\u5728JS\u4e2d\uff0c\u6570\u503c\u9ed8\u8ba4\u90fd\u662f64\u4f4d\u53cc\u7cbe\u5ea6\u7684\uff0c\u7cbe\u5ea6\u5f88\u9ad8\uff0c\u4f46\u662f\uff0c\u6709\u65f6\u5019\u6211\u4eec\u53ea\u9700\u898132\u4f4d\u5355\u7cbe\u5ea6\uff0c\u4f8b\u5982\u6570\u503c\u6e90\u81ea\u4e8e Float32Array \u6570\u636e\u7684\u65f6\u5019\uff0c\u6b64\u65f6\uff0c\u4f60\u4f1a\u53d1\u73b0\u867d\u7136\u6570\u5b57\u770b\u8d77\u6765\u662f\u76f8\u540c\u7684\uff0c\u4f46\u662f32\u4f4d\u6d6e\u70b9\u548c64\u4f4d\u6d6e\u70b9\u6570\u65e0\u6cd5\u76f8\u7b49\u3002<\/p>\n<p>\u4e3a\u4e86\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\uff0c\u5c31\u6709\u4e86<code>Math.fround()<\/code>\u65b9\u6cd5\uff0c\u53ef\u4ee5\u628a64\u4f4d\u6d6e\u70b9\u6570\u8f6c\u6362\u621032\u4f4d\u6d6e\u70b9\u6570\u3002<\/p>\n<p>\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u5728\u5185\u90e8\uff0cJavaScript\u4ecd\u7136\u628a\u53c2\u6570x\u89c6\u4e3a64\u4f4d\u6d6e\u70b9\uff0c\u5b83\u53ea\u662f\u5728\u5c3e\u6570\u7684\u7b2c23\u4f4d\uff08\u5c0f\u6570\u7b2c7\u4f4d\uff09\u6267\u884c\u201c\u820d\u5165\u5230\u5076\u6570\u201d\uff0c\u5e76\u5c06\u540e\u9762\u6240\u6709\u5c3e\u6570\u4f4d\u8bbe\u7f6e\u4e3a0\u3002<\/p>\n<p>\u4f8b\u5982\u6211\u4eec\u4f7f\u7528Math.random()\u968f\u673a\u8fd4\u56de\u4e00\u4e2a\u53cc\u7cbe\u5ea6\u6d6e\u70b9\u503c\uff0c\u7ed3\u679c\u662f0.8602673475467222\uff0c\u7136\u540e\u4f5c\u4e3a\u53c2\u6570\u5e94\u7528\u5728<code>Math.fround()<\/code>\u65b9\u6cd5\u4e2d\uff0c\u7ed3\u679c\u4e0b\u9762\u8fd9\u4e9b\u503c\u7ed3\u679c\u90fd\u662f\u4e00\u6837\u7684\uff1a<\/p>\n<pre>Math.fround(0.8602673475467222);    <span style=\"color:green;\">\/\/ 0.8602673411369324<\/span>\r\nMath.fround(0.8602673499999999);    <span style=\"color:green;\">\/\/ 0.8602673411369324<\/span>\r\nMath.fround(0.8602673400000000);    <span style=\"color:green;\">\/\/ 0.8602673411369324<\/span>\r\nMath.fround(0.86026733);            <span style=\"color:green;\">\/\/ 0.8602673411369324<\/span><\/pre>\n<p>\u4e4b\u6240\u4ee5\u6700\u7ec8\u7684\u503c\u90fd\u662f\u4e00\u6837\u7684\uff0c\u662f\u56e0\u4e3a\u5c0f\u6570\u70b9\u7b2c7\u4f4d\u4e4b\u540e\u7684\u503c\u90fd\u88ab\u5f53\u505a0\u5904\u7406\u4e86\u3002<\/p>\n<p><strong>\u4f7f\u7528\u6848\u4f8b<\/strong><\/p>\n<p>\u6570\u5b571.5\u53ef\u4ee5\u5728\u4e8c\u8fdb\u5236\u6570\u5b57\u7cfb\u7edf\u4e2d\u7cbe\u786e\u8868\u793a\uff0c\u6240\u4ee5\u572832\u4f4d\u548c64\u4f4d\u4e2d\u76f8\u540c\uff1a<\/p>\n<pre>Math.fround(1.5);            <span style=\"color:green;\">\/\/ 1.5<\/span>\r\nMath.fround(1.5) === 1.5;    <span style=\"color:green;\">\/\/ true<\/span><\/pre>\n<p>\u6570\u5b571.337\u4e0d\u80fd\u5728\u4e8c\u8fdb\u5236\u6570\u5b57\u7cfb\u7edf\u4e2d\u7cbe\u786e\u8868\u793a\uff0c\u56e0\u6b64\u5b83\u768432\u4f4d\u548c64\u4f4d\u503c\u662f\u4e0d\u76f8\u7b49\u7684\uff1a<\/p>\n<pre>Math.fround(1.337);              <span style=\"color:green;\">\/\/ 1.3370000123977661<\/span>\r\nMath.fround(1.337) === 1.337;    <span style=\"color:green;\">\/\/ false<\/span><\/pre>\n<p>\u5982\u679c\u503c\u592a\u5927\uff0c\u8d85\u8fc7\u4e8632\u4f4d\u6d6e\u70b9\u503c\u7684\u9650\u5236\uff0c\u5219\u8fd4\u56deInfinity\uff0c\u5982\u679c\u503c\u5c0f\u5230\u8d85\u51fa\u8303\u56f4\u9650\u5236\uff0c\u5219\u8fd4\u56de-Infinity\uff1a<\/p>\n<pre>2 ** 150;                 <span style=\"color:green;\">\/\/ 1.42724769270596e+45<\/span>\r\nMath.fround(2 ** 150);    <span style=\"color:green;\">\/\/ Infinity<\/span><\/pre>\n<p>\u5982\u679c\u53c2\u6570\u4e0d\u662f\u4e00\u4e2a\u6570\u503c\uff0c\u6216\u8005\u53c2\u6570\u503c\u662fNaN\uff0c\u5219\u8fd4\u56deNaN\uff1a<\/p>\n<pre>Math.fround('abc');    <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.fround(NaN);      <span style=\"color:green;\">\/\/ NaN<\/span><\/pre>\n<p><code>Math.fround()<\/code>\u65b9\u6cd5IE\u6d4f\u89c8\u5668\u662f\u4e0d\u8ba4\u8bc6\u7684\uff0c\u5982\u679c\u9879\u76ee\u53ea\u9700\u8981\u517c\u5bb9\u5230IE10+\u6d4f\u89c8\u5668\uff0c\u5219\u53ef\u4ee5\u4f7f\u7528\u4e0b\u9762\u7684Polyfill\uff0c\u501f\u52a9Float32Array\u5bf9\u8c61\uff1a<\/p>\n<pre>Math.fround = Math.fround || (function (array) {\r\n  return function(x) {\r\n    return array[0] = x, array[0];\r\n  };\r\n})(new Float32Array(1));<\/pre>\n<p>\u5982\u679c\u8fd8\u9700\u8981\u517c\u5bb9IE9\uff0c\u751a\u81f3IE8\u6d4f\u89c8\u5668\uff0c\u5219\u53ef\u4ee5\u4f7f\u7528\u4e0b\u9762\u8fd9\u4e2aPolyfill\uff1a<\/p>\n<pre>if (!Math.fround) Math.fround = function(arg) {\r\n  arg = Number(arg);\r\n  <span style=\"color:green;\">\/\/ \u5982\u679c\u662f \u00b10 \u548c NaN \u76f4\u63a5\u8fd4\u56de<\/span>\r\n  if (!arg) return arg;\r\n  var sign = arg < 0 ? -1 : 1;\r\n  if (sign < 0) arg = -arg;\r\n  <span style=\"color:green;\">\/\/ \u8ba1\u7b97\u6307\u6570\uff088\u4f4d\uff0c\u6709\u7b26\u53f7\uff09\u3002<\/span>\r\n  var exp = Math.floor(Math.log(arg) \/ Math.LN2);\r\n  var powexp = Math.pow(2, Math.max(-126, Math.min(exp, 127)));\r\n  <span style=\"color:green;\">\/\/ \u5904\u7406\u6bd4\u8f83\u5c0f\u7684\u503c\uff1a\u5982\u679c\u6307\u6570\u4f4d\u90fd\u4e3a\u96f6\uff0c\u5219\u524d\u5bfc\u6570\u5b57\u4e3a\u96f6\u3002<\/span>\r\n  var leading = exp < -127 ? 0 : 1;\r\n  <span style=\"color:green;\">\/\/ \u5c3e\u657023\u4f4d\u4e4b\u540e\u7684\u53d8\u62100\u3002<\/span>\r\n  var mantissa = Math.round((leading - arg \/ powexp) * 0x800000);\r\n  if (mantissa <= -0x800000) return sign * Infinity;\r\n  return sign * powexp * (leading - mantissa \/ 0x800000);\r\n};<\/pre>\n<h4>Math.imul(x, y)<\/h4>\n<p>\u5c06\u4e24\u4e2a32\u4f4d\u6574\u6570x\u548cy\u76f8\u4e58\uff0c\u5e76\u8fd4\u56de\u7c7bC\u768432\u4f4d\u7ed3\u679c\u3002<\/p>\n<p>\u8fd9\u662f\u76ee\u524dJS\u4e2d\u552f\u4e00\u4e00\u4e2a32\u4f4d\u7684\u57fa\u672c\u6570\u5b66\u8fd0\u7b97\uff0c\u53ef\u80fd\u6709\u4eba\u4f7f\u7528\u8fc7JavaScript\u64cd\u4f5c\u7b26\u6a21\u62df32\u4f4d\u8fd0\u7b97\u3002\u4f8b\u5982\uff0cidiv\u53ef\u4ee5\u5b9e\u73b0\u5982\u4e0b\uff1a<\/p>\n<pre>function idiv(x, y) {\r\n    return (x \/ y) | 0;\r\n}<\/pre>\n<p>\u8fd9\u79cd\u6a21\u62df\u662f\u4e0d\u884c\u7684\uff0c\u5c06\u4e24\u4e2a32\u4f4d\u5927\u6574\u6570\u76f8\u4e58\u53ef\u80fd\u4f1a\u4ea7\u751f\u4e00\u4e2a\u8fc7\u5927\u7684\u53cc\u7cbe\u5ea6\u6570\uff0c\u5bfc\u81f4\u9760\u540e\u7684\u5f88\u591a\u4f4d\u6570\u4e22\u5931\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.imul(2, 4);          <span style=\"color:green;\">\/\/ 8<\/span>\r\nMath.imul(-1, 8);         <span style=\"color:green;\">\/\/ -8<\/span>\r\nMath.imul(-2, -2);        <span style=\"color:green;\">\/\/ 4<\/span>\r\nMath.imul(0xffffffff, 5); <span style=\"color:green;\">\/\/ -5<\/span>\r\nMath.imul(0xfffffffe, 5); <span style=\"color:green;\">\/\/ -10<\/span><\/pre>\n<p>IE\u6d4f\u89c8\u5668\u7684Polyfill\u5982\u4e0b\uff1a<\/p>\n<pre>if (!Math.imul) Math.imul = function(a, b) {\r\n  var aHi = (a >>> 16) & 0xffff;\r\n  var aLo = a & 0xffff;\r\n  var bHi = (b >>> 16) & 0xffff;\r\n  var bLo = b & 0xffff;\r\n  <span style=\"color:green;\">\/\/ 0\u7684\u79fb\u4f4d\u56fa\u5b9a\u4e86\u9ad8\u4f4d\u90e8\u5206\u7684\u7b26\u53f7\r\n  \/\/ \u6700\u540e\u7684| 0\u5c06\u65e0\u7b26\u53f7\u503c\u8f6c\u6362\u4e3a\u6709\u7b26\u53f7\u503c<\/span>\r\n  return ((aLo * bLo) + (((aHi * bLo + aLo * bHi) << 16) >>> 0) | 0);\r\n};<\/pre>\n<h4>Math.clz32(x)<\/h4>\n<p><code>Math.clz32()<\/code>\u8fd4\u56de\u53c2\u6570x\u768432\u4f4d\u4e8c\u8fdb\u5236\u8868\u793a\u5f62\u5f0f\u4e2d\u7684\u524d\u5bfc\u96f6\u4f4d\u6570\u3002<\/p>\n<p>\u201cclz32\u201d\u662fCountLeadingZeroes32\u7684\u7f29\u5199\u3002<\/p>\n<p>\u5982\u679cx\u4e0d\u662f\u6570\u5b57\uff0c\u5219\u5b83\u5c06\u9996\u5148\u8f6c\u6362\u4e3a\u6570\u5b57\uff0c\u7136\u540e\u8f6c\u6362\u4e3a32\u4f4d\u65e0\u7b26\u53f7\u6574\u6570\u3002<\/p>\n<p>\u5982\u679c\u8f6c\u6362\u540e\u768432\u4f4d\u65e0\u7b26\u53f7\u6574\u6570\u662f0\uff0c\u5219\u8fd4\u56de32\uff0c\u56e0\u4e3a\u6240\u6709\u4f4d\u90fd\u662f0\u3002<\/p>\n<p>\u8fd9\u4e2a\u51fd\u6570\u5bf9\u4e8e\u7f16\u8bd1\u6210JS\u7684\u7cfb\u7edf\u7279\u522b\u6709\u7528\uff0c\u6bd4\u5982Emscripten\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre><span style=\"color:green;\">\/\/ 00000000000000000000000000000001<\/span>\r\nconsole.log(Math.clz32(1));\r\n<span style=\"color:green;\">\/\/ \u9884\u671f\u8f93\u51fa: 31<\/span>\r\n\r\n<span style=\"color:green;\">\/\/ 00000000000000000000000000000100<\/span>\r\nconsole.log(Math.clz32(4));\r\n<span style=\"color:green;\">\/\/ \u9884\u671f\u8f93\u51fa: 29<\/span>\r\n\r\n<span style=\"color:green;\">\/\/ 00000000000000000000001111101000<\/span>\r\nconsole.log(Math.clz32(1000));\r\n<span style=\"color:green;\">\/\/ \u9884\u671f\u8f93\u51fa: 22<\/span>\r\n\r\n\r\nMath.clz32(1);           <span style=\"color:green;\">\/\/ 31<\/span>\r\nMath.clz32(1000);        <span style=\"color:green;\">\/\/ 22<\/span>\r\nMath.clz32();            <span style=\"color:green;\">\/\/ 32<\/span>\r\n\r\nvar stuff = [NaN, Infinity, -Infinity, 0, -0, null, undefined, 'foo', {}, []];\r\nstuff.every(n => Math.clz32(n) == 32);  <span style=\"color:green;\">\/\/ true<\/span>\r\n\r\nMath.clz32(true);        <span style=\"color:green;\">\/\/ 31<\/span>\r\nMath.clz32(3.5);         <span style=\"color:green;\">\/\/ 30<\/span><\/pre>\n<p>\u4e0b\u9762\u7684polyfill\u662f\u6700\u6709\u6548\u7684\uff1a<\/p>\n<pre>if (!Math.clz32) Math.clz32 = (function(log, LN2){\r\n  return function(x) {\r\n    var asUint = x >>> 0;\r\n    if (asUint === 0) {\r\n      return 32;\r\n    }\r\n    return 31 - (log(asUint) \/ LN2 | 0) |0; <span style=\"color:green;\">\/\/ \"| 0\" \u4f5c\u7528\u7c7b\u4f3c\u4e8emath.floor<\/span>\r\n  };\r\n})(Math.log, Math.LN2);<\/pre>\n<h4>Math.hypot(...values)<\/h4>\n<p><code>Math.hypot()<\/code>\u8fd4\u56de\u53c2\u6570\u5e73\u65b9\u548c\u7684\u5e73\u65b9\u6839\u3002<\/p>\n<p>\u8bed\u6cd5\uff1a<\/p>\n<pre>Math.hypot([value1[, value2[, ...]]]);<\/pre>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.hypot(3, 4);        <span style=\"color:green;\">\/\/ 5<\/span>\r\nMath.hypot(3, 4, 5);     <span style=\"color:green;\">\/\/ 7.0710678118654755<\/span>\r\nMath.hypot();            <span style=\"color:green;\">\/\/ 0<\/span>\r\nMath.hypot(NaN);         <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.hypot(3, 4, 'foo'); <span style=\"color:green;\">\/\/ NaN, +'foo' => NaN<\/span>\r\nMath.hypot(3, 4, '5');   <span style=\"color:green;\">\/\/ 7.0710678118654755, +'5' => 5<\/span>\r\nMath.hypot(-3);          <span style=\"color:green;\">\/\/ 3, the same as Math.abs(-3)<\/span><\/pre>\n<p>IE\u6d4f\u89c8\u5668\u4e0d\u652f\u6301\u6b64\u65b9\u6cd5\uff0c\u53ef\u4ee5\u5f15\u5165\u4e0b\u9762\u7684JS\u4ee3\u7801\u4f7f\u4e4b\u517c\u5bb9\uff1a<\/p>\n<pre>if (!Math.hypot) Math.hypot = function() {\r\n  var y = 0, i = arguments.length;\r\n  while (i--) y += arguments[i] * arguments[i];\r\n  return Math.sqrt(y);\r\n};<\/pre>\n<p>\u6b64\u65b9\u6cd5\u9002\u5408\u8ba1\u7b97\u4e24\u4e2a\u70b9\u4e4b\u95f4\u7684\u8ddd\u79bb\u3002<\/p>\n<pre>let distance = Math.hypot(y2-y1, x2-x1);<\/pre>\n<h4>Math.sinh(x)<\/h4>\n<p><code>Math.sinh()<\/code>\u8fd4\u56de\u53c2\u6570x\u7684\u53cc\u66f2\u6b63\u5f26\u503c\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.sinh(0);    <span style=\"color:green;\">\/\/ 0<\/span>\r\nMath.sinh(1);    <span style=\"color:green;\">\/\/ 1.1752011936438014<\/span>\r\nMath.sinh(-1);   <span style=\"color:green;\">\/\/ -1.1752011936438014<\/span>\r\nMath.sinh(2);    <span style=\"color:green;\">\/\/ 3.626860407847019<\/span><\/pre>\n<p>Polyfill\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre>Math.sinh = Math.sinh || function(x) {\r\n  return (Math.exp(x) - Math.exp(-x)) \/ 2;\r\n}<\/pre>\n<h4>Math.cosh(x)<\/h4>\n<p><code>Math.cosh()<\/code>\u8fd4\u56de\u53c2\u6570x\u7684\u53cc\u66f2\u4f59\u5f26\u503c\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.cosh(0);    <span style=\"color:green;\">\/\/ 1<\/span>\r\nMath.cosh(1);    <span style=\"color:green;\">\/\/ 1.543080634815244<\/span>\r\nMath.cosh(-1);   <span style=\"color:green;\">\/\/ 1.543080634815244<\/span>\r\nMath.cosh(2);    <span style=\"color:green;\">\/\/ 3.7621956910836314<\/span><\/pre>\n<p>Polyfill\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre>Math.cosh = Math.cosh || function(x) {\r\n  return (Math.exp(x) + Math.exp(-x)) \/ 2;\r\n}<\/pre>\n<h4>Math.tanh(x)<\/h4>\n<p><code>Math.tanh()<\/code>\u8fd4\u56de\u53c2\u6570x\u7684\u53cc\u66f2\u6b63\u5207\u503c\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.tanh(0);        <span style=\"color:green;\">\/\/ 0<\/span>\r\nMath.tanh(Infinity); <span style=\"color:green;\">\/\/ 1<\/span>\r\nMath.tanh(1);        <span style=\"color:green;\">\/\/ 0.7615941559557649<\/span>\r\nMath.tanh(-1);       <span style=\"color:green;\">\/\/ -0.7615941559557649<\/span><\/pre>\n<p>Polyfill\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre>Math.tanh = Math.tanh || function(x){\r\n    var a = Math.exp(+x), b = Math.exp(-x);\r\n    return a == Infinity ? 1 : b == Infinity ? -1 : (a - b) \/ (a + b);\r\n}<\/pre>\n<h4>Math.asinh(x)<\/h4>\n<p><code>Math.asinh()<\/code>\u8fd4\u56de\u53c2\u6570x\u7684\u53cd\u53cc\u66f2\u6b63\u5f26\u503c\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.asinh(1);    <span style=\"color:green;\">\/\/ 0.881373587019543<\/span>\r\nMath.asinh(0);   <span style=\"color:green;\">\/\/ 0<\/span>\r\nMath.asinh(-1);  <span style=\"color:green;\">\/\/ -0.881373587019543<\/span>\r\nMath.asinh(2)    <span style=\"color:green;\">\/\/ 1.4436354751788103<\/span><\/pre>\n<p>Polyfill\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre>Math.asinh = Math.asinh || function(x) {\r\n  if (x === -Infinity) {\r\n    return x;\r\n  } else {\r\n    return Math.log(x + Math.sqrt(x * x + 1));\r\n  }\r\n};<\/pre>\n<h4>Math.acosh(x)<\/h4>\n<p><code>Math.acosh()<\/code>\u8fd4\u56de\u53c2\u6570x\u7684\u53cd\u53cc\u66f2\u4f59\u5f26\u503c\u3002<\/p>\n<p>\u5c0f\u4e8e1\u7684\u53c2\u6570\u4f1a\u8fd4\u56deNaN\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.acosh(-1);  <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.acosh(0);   <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.acosh(0.5); <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.acosh(1);   <span style=\"color:green;\">\/\/ 0<\/span>\r\nMath.acosh(2);   <span style=\"color:green;\">\/\/ 1.3169578969248166<\/span><\/pre>\n<p>Polyfill\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre>Math.acosh = Math.acosh || function(x) {\r\n  return Math.log(x + Math.sqrt(x * x - 1));\r\n};<\/pre>\n<h4>Math.atanh(x)<\/h4>\n<p><code>Math.atanh()<\/code>\u8fd4\u56de\u53c2\u6570x\u7684\u53cd\u53cc\u66f2\u6b63\u5207\u503c\u3002<\/p>\n<p>\u5c0f\u4e8e1\u6216\u8005\u5927\u4e8e1\u7684\u53c2\u6570\u4f1a\u8fd4\u56deNaN\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Math.atanh(-2);  <span style=\"color:green;\">\/\/ NaN<\/span>\r\nMath.atanh(-1);  <span style=\"color:green;\">\/\/ -Infinity<\/span>\r\nMath.atanh(0);   <span style=\"color:green;\">\/\/ 0<\/span>\r\nMath.atanh(0.5); <span style=\"color:green;\">\/\/ 0.5493061443340548<\/span>\r\nMath.atanh(1);   <span style=\"color:green;\">\/\/ Infinity<\/span>\r\nMath.atanh(2);   <span style=\"color:green;\">\/\/ NaN<\/span><\/pre>\n<p>Polyfill\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre>Math.atanh = Math.atanh || function(x) {\r\n  return Math.log((1+x)\/(1-x)) \/ 2;\r\n};<\/pre>\n<h3>\u4e8c\u3001ES6\u4e2d\u7684Number\u65b9\u6cd5<\/h3>\n<h4>Number.isFinite(number)<\/h4>\n<p><code>Number.isFinite()<\/code>\u65b9\u6cd5\u7528\u6765\u786e\u5b9a\u4f20\u9012\u7684\u503c\u662f\u5426\u4e3a\u6709\u9650\u503c\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Number.isFinite(Infinity);  <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isFinite(NaN);       <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isFinite(-Infinity); <span style=\"color:green;\">\/\/ false<\/span>\r\n\r\nNumber.isFinite(0);         <span style=\"color:green;\">\/\/ true<\/span>\r\nNumber.isFinite(2e64);      <span style=\"color:green;\">\/\/ true<\/span>\r\n\r\nNumber.isFinite('0');       <span style=\"color:green;\">\/\/ false, \u5168\u5c40\u7684isFinite('0')\u8fd4\u56de\u503c\u662ftrue<\/span>\r\nNumber.isFinite(null);      <span style=\"color:green;\">\/\/ false, \u5168\u5c40\u7684isFinite(null)\u8fd4\u56de\u503c\u662ftrue<\/span><\/pre>\n<p>\u5982\u679c\u60f3\u8981\u5728\u4f4e\u7248\u672c\u6d4f\u89c8\u5668\u4e2d\u4f7f\u7528\uff0c\u53ef\u4ee5\u5f15\u5165\u4e0b\u9762\u8fd9\u6bb5JavaScript\u811a\u672c\uff1a<\/p>\n<pre>if (Number.isFinite === undefined) Number.isFinite = function(value) {\r\n    return typeof value === 'number' && isFinite(value);\r\n}<\/pre>\n<h4>Number.isNaN(number)<\/h4>\n<p><code>Number.isNaN()<\/code>\u65b9\u6cd5\u7528\u6765\u5224\u65ad\u53c2\u6570x\u662f\u5426\u662fNaN\uff0c\u540c\u65f6\u7c7b\u578b\u662fNumber\uff0c\u8fd9\u662f\u4e00\u4e2a\u6bd4\u6700\u521d\u7684\u3001\u5168\u5c40\u7684<code>isNaN()<\/code>\u65b9\u6cd5\u66f4\u5065\u58ee\u7684\u7248\u672c\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Number.isNaN(NaN);        <span style=\"color:green;\">\/\/ true<\/span>\r\nNumber.isNaN(Number.NaN); <span style=\"color:green;\">\/\/ true<\/span>\r\nNumber.isNaN(0 \/ 0);      <span style=\"color:green;\">\/\/ true<\/span>\r\n\r\n<span style=\"color:green;\">\/\/ \u4e0b\u9762\u8fd9\u4e9b\u53c2\u6570\u5982\u679c\u4f7f\u7528\u5168\u5c40\u7684isNaN()\u65b9\u6cd5\u90fd\u662f\u8fd4\u56detrue<\/span>\r\nNumber.isNaN('NaN');      <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isNaN(undefined);  <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isNaN({});         <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isNaN('blabla');   <span style=\"color:green;\">\/\/ false<\/span>\r\n\r\n<span style=\"color:green;\">\/\/ \u4e0b\u9762\u7684\u5168\u90e8\u8fd4\u56defalse<\/span>\r\nNumber.isNaN(true);\r\nNumber.isNaN(null);\r\nNumber.isNaN(37);\r\nNumber.isNaN('37');\r\nNumber.isNaN('37.37');\r\nNumber.isNaN('');\r\nNumber.isNaN(' ');<\/pre>\n<p>\u6b64\u65b9\u6cd5\u5e76\u4e0d\u662f\u6240\u6709\u6d4f\u89c8\u5668\u90fd\u652f\u6301\u7684\uff0c\u9700\u8981\u6253\u4e2a\u5c0f\u8865\u4e01\uff1a<\/p>\n<pre>Number.isNaN = Number.isNaN || function isNaN(input) {\r\n    return typeof input === 'number' && input !== input;\r\n}<\/pre>\n<h4>Number.parseFloat\u548cNumber.parseInt<\/h4>\n<p>\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre>Number.parseFloat(string)\r\nNumber.parseInt(string, radix)<\/pre>\n<p>Number.parseFloat\u65b9\u6cd5\u548c\u5168\u5c40\u7684parseFloat\u65b9\u6cd5\u662f\u4e00\u6837\u7684\u65b9\u6cd5\u3002<\/p>\n<pre>Number.parseFloat === parseFloat;    <span style=\"color:green;\">\/\/ true<\/span><\/pre>\n<p>Number.parseInt\u65b9\u6cd5\u548c\u5168\u5c40\u7684parseInt\u65b9\u6cd5\u662f\u4e00\u6837\u7684\u65b9\u6cd5\u3002<\/p>\n<pre>Number.parseInt === parseInt;    <span style=\"color:green;\">\/\/ true<\/span><\/pre>\n<h4>Number.EPSILON<\/h4>\n<p>Number.EPSILON\u662f\u4e00\u4e2a\u6570\u503c\u5f88\u5c0f\u7684\u5e38\u91cf\uff1a<\/p>\n<pre>Number.EPSILON == 2.220446049250313e-16;    <span style=\"color:green;\">\/\/ true<\/span><\/pre>\n<p>\u53ef\u4ee5\u7528\u6765\u51c6\u786e\u6bd4\u8f83\u6d6e\u70b9\u503c\u3002<\/p>\n<p>\u4f8b\u5982\uff1a<\/p>\n<pre>0.1 + 0.2 === 0.3;    <span style=\"color:green;\">\/\/ false<\/span><\/pre>\n<p>\u53ef\u4ee5\u501f\u52a9Number.EPSILON\u8fdb\u884c\u51c6\u5907\u6bd4\u8f83\uff1a<\/p>\n<pre>function epsEqu(x, y) {\r\n    return Math.abs(x - y) < Number.EPSILON;\r\n}\r\nconsole.log(epsEqu(0.1+0.2, 0.3));   <span style=\"color:green;\">\/\/ true<\/span><\/pre>\n<h4>Number.isInteger(number)<\/h4>\n<p>JavaScript\u53ea\u6709\u6d6e\u70b9\u6570\uff08\u53cc\u7cbe\u5ea6\uff09\u3002\u56e0\u6b64\uff0c\u6574\u6570\u53ea\u662f\u4e0d\u5e26\u5c0f\u6570\u7684\u6d6e\u70b9\u6570\u3002<\/p>\n<p><code>Number.isInteger()<\/code>\u65b9\u6cd5\u53ef\u4ee5\u5224\u5b9a\u6570\u5b57\u662f\u4e0d\u662f\u6ca1\u6709\u5c0f\u6570\uff0c\u5982\u679c\u6ca1\u6709\uff0c\u5219\u8fd4\u56de<code>true<\/code>\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Number.isInteger(0);         <span style=\"color:green;\">\/\/ true<\/span>\r\nNumber.isInteger(1);         <span style=\"color:green;\">\/\/ true<\/span>\r\nNumber.isInteger(-100000);   <span style=\"color:green;\">\/\/ true<\/span>\r\nNumber.isInteger(99999999999999999999999); \/\/ true<\/span>\r\n\r\nNumber.isInteger(0.1);       <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isInteger(Math.PI);   <span style=\"color:green;\">\/\/ false<\/span>\r\n\r\nNumber.isInteger(NaN);       <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isInteger(Infinity);  <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isInteger(-Infinity); <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isInteger('10');      <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isInteger(true);      <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isInteger(false);     <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isInteger([1]);       <span style=\"color:green;\">\/\/ false<\/span>\r\n\r\nNumber.isInteger(5.0);       <span style=\"color:green;\">\/\/ true<\/span>\r\nNumber.isInteger(5.000000000000001); <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isInteger(5.0000000000000001); <span style=\"color:green;\">\/\/ true<\/span><\/pre>\n<p>\u7531\u4e8e\u662f\u65b0\u7279\u6027\uff0c\u4e0d\u662f\u6240\u6709\u6d4f\u89c8\u5668\u90fd\u652f\u6301\u8fd9\u4e2a\u65b9\u6cd5\uff0c\u5982\u679c\u60f3\u8981\u989d\u5916\u517c\u5bb9\u4e0b\uff0c\u53ef\u4ee5\u53c2\u8003\u4e0b\u9762\u7684\u8bed\u53e5\uff1a<\/p>\n<pre>Number.isInteger = Number.isInteger || function(value) {\r\n  return typeof value === 'number' &&\r\n    isFinite(value) &&\r\n    Math.floor(value) === value;\r\n};<\/pre>\n<h4>Safe Integers<\/h4>\n<p>\u68c0\u6d4b\u662f\u5426\u662f\u5408\u6cd5\u8303\u56f4\u5185\u7684\u6574\u6570\u3002\u5305\u62ec\u4e0b\u97621\u4e2a\u65b9\u6cd5\u548c2\u4e2a\u5e38\u91cf\uff1a<\/p>\n<ul>\n<li>Number.isSafeInteger(number)<\/li>\n<li>Number.MIN_SAFE_INTEGER<\/li>\n<li>Number.MAX_SAFE_INTEGER<\/li>\n<\/ul>\n<p>\u5176\u4e2d\uff0cNumber.MIN_SAFE_INTEGER\u8868\u793a\u867d\u5c0f\u5b89\u5168\u6574\u6570\uff0cNumber.MAX_SAFE_INTEGER\u8868\u793a\u6700\u5927\u5b89\u5168\u6574\u6570\uff0c\u5206\u522b\u662f\u22122^53^ + 1\u548c2^53^ - 1\uff0c\u5177\u4f53\u503c\u662f-9007199254740991\u548c9007199254740991\u3002<\/p>\n<p><code>Number.isSafeInteger()<\/code>\u65b9\u6cd5\u7528\u6765\u5224\u65ad\u53c2\u6570\u503c\u662f\u5426\u5728\u5b89\u5168\u7684\u6574\u6570\u8303\u56f4\u5185\u3002<\/p>\n<p>\u4f7f\u7528\u793a\u610f\uff1a<\/p>\n<pre>Number.isSafeInteger(3);                    <span style=\"color:green;\">\/\/ true<\/span>\r\nNumber.isSafeInteger(Math.pow(2, 53));      <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isSafeInteger(Math.pow(2, 53) - 1);  <span style=\"color:green;\">\/\/ true<\/span>\r\nNumber.isSafeInteger(NaN);                  <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isSafeInteger(Infinity);             <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isSafeInteger('3');                  <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isSafeInteger(3.1);                  <span style=\"color:green;\">\/\/ false<\/span>\r\nNumber.isSafeInteger(3.0);                  <span style=\"color:green;\">\/\/ true<\/span><\/pre>\n<p>\u6b64\u65b9\u6cd5\u6709\u517c\u5bb9\u6027\u8981\u6c42\uff0c\u53ef\u4ee5\u4f7f\u7528\u4e0b\u9762\u7684JS\u4ee3\u7801\u4fee\u6b63\uff1a<\/p>\n<pre>Number.isSafeInteger = Number.isSafeInteger || function (value) {\r\n   return Number.isInteger(value) && Math.abs(value) <= Number.MAX_SAFE_INTEGER;\r\n};<\/pre>\n<h3>\u4e09\u3001ES6\u4e2d\u7684\u5176\u5b83\u6570\u503c\u53d8\u5316<\/h3>\n<p>ES6\u4e2d\u53ef\u4ee5\u4f7f\u7528\u4e8c\u8fdb\u5236\u548c\u516b\u8fdb\u5236\u8868\u793a\u6cd5\u6307\u5b9a\u6574\u6570\uff0c\u4f8b\u5982\uff1a<\/p>\n<pre>0xFF <span style=\"color:green;\">\/\/ ES5: \u5341\u516d\u8fdb\u5236<\/span>\r\n\u7ed3\u679c\u662f\uff1a255\r\n0b11 <span style=\"color:green;\">\/\/ ES6: \u4e8c\u8fdb\u5236<\/span>\r\n\u7ed3\u679c\u662f\uff1a3\r\n0o10 <span style=\"color:green;\">\/\/ ES6: \u516b\u8fdb\u5236<\/span>\r\n\u7ed3\u679c\u662f\uff1a8<\/pre>\n<p>parseInt()\u65b9\u6cd5\u53ef\u4ee5\u89e3\u6790\u5341\u516d\u8fdb\u5236\u8868\u793a\u7684\u5b57\u7b26\u4e32\uff0c\u4f8b\u5982\uff1a<\/p>\n<pre>parseInt('0xFF');         <span style=\"color:green;\">\/\/ 255<\/span>\r\nparseInt('0xFF', 0);      <span style=\"color:green;\">\/\/ 255<\/span>\r\nparseInt('0xFF', 16)      <span style=\"color:green;\">\/\/ 255<\/span><\/pre>\n<p>\u4f46\u662f\u5982\u679c\u6307\u5b9a\u5176\u4ed6\u8fdb\u5236\u4f1a\u8ba4\u4e3a\u662f0\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<pre>parseInt('0xFF', 10);    <span style=\"color:green;\">\/\/ 0<\/span>\r\nparseInt('0xFF', 17);    <span style=\"color:green;\">\/\/ 0<\/span><\/pre>\n<p>ES6\u652f\u6301\u4e86\u6570\u503c\u5176\u4ed6\u8868\u793a\u65b9\u6cd5\uff0c\u4f8b\u59820b11\u8868\u793a3\uff0c0o10\u8868\u793a8\uff0c\u4f46\u662f\uff0c<code>parseInt()<\/code>\u65b9\u6cd5\u5728ES6\u4e2d\u5e76\u6ca1\u6709\u540c\u6b65\u5347\u7ea7\uff0c\u56e0\u6b64\uff0c\u76f4\u63a5<code>parseInt('0b11')<\/code>\u6216\u8005<code>parseInt('0o10')<\/code>\u4e0d\u4f1a\u8fd4\u56de\u5bf9\u5e94\u7684\u8fdb\u5236\u503c\uff0c\u5982\u4e0b\u793a\u610f\uff1a<\/p>\n<pre>parseInt('0b111');       <span style=\"color:green;\">\/\/ 0<\/span>\r\nparseInt('0b111', 2);    <span style=\"color:green;\">\/\/ 0<\/span>\r\nparseInt('111');         <span style=\"color:green;\">\/\/ 7<\/span>\r\n\r\nparseInt('0o10');       <span style=\"color:green;\">\/\/ 0<\/span>\r\nparseInt('0o10', 8);    <span style=\"color:green;\">\/\/ 0<\/span>\r\nparseInt('10', 8);      <span style=\"color:green;\">\/\/ 8<\/span><\/pre>\n<p>\u53ef\u4ee5\u4f7f\u7528Number()\u65b9\u6cd5\u8fdb\u884c\u8f6c\u5316\uff1a<\/p>\n<pre>Number('0b111');    <span style=\"color:green;\">\/\/ 7<\/span>\r\nNumber('0o10');     <span style=\"color:green;\">\/\/ 8<\/span><\/pre>\n<h3>\u56db\u3001\u7ed3\u675f\u8bed<\/h3>\n<p>\u5927\u91cf\u6848\u4f8b\u548cPolyfill\u4ee3\u7801\u6574\u7406\u81eaMDN\u6587\u6863\u3002<\/p>\n<p>\u5176\u4e2d\u6709\u4e9b\u6570\u5b66\u65b9\u6cd5\u6bd4\u8f83\u5b9e\u7528\uff0c\u4f8b\u5982<code>Math.hypot()<\/code>\u65b9\u6cd5\uff0c\u6709\u4e9b\u6570\u5b66\u5904\u7406\u65b9\u6cd5\u6211\u4eec\u5f88\u5c11\u6709\u673a\u4f1a\u7528\u5230\uff0c\u4f8b\u5982<code>Math.clz32()<\/code>\u65b9\u6cd5\u3002<\/p>\n<p>\u6574\u7406\u7684\u8fc7\u7a0b\u4e2d\u8fd8\u662f\u5b66\u5230\u4e0d\u5c11\u4e1c\u897f\u7684\uff0c\u5e0c\u671b\u4e00\u6bb5\u65f6\u95f4\u540e\u8fd8\u8bb0\u5f97\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/\/image.zhangxinxu.com\/image\/emtion\/emoji\/1f604.svg\" width=\"20\" height=\"20\" align=\"absmiddle\"><\/p>\n<p>\u672c\u6587\u4e3a\u539f\u521b\u6587\u7ae0\uff0c\u6b22\u8fce\u5206\u4eab\uff0c\u52ff\u5168\u6587\u8f6c\u8f7d\uff0c\u5982\u679c\u5b9e\u5728\u559c\u6b22\uff0c\u53ef\u6536\u85cf\uff0c\u6c38\u4e0d\u8fc7\u671f\uff0c\u4e14\u4f1a\u53ca\u65f6\u66f4\u65b0\u77e5\u8bc6\u70b9\u53ca\u4fee\u6b63\u9519\u8bef\uff0c\u9605\u8bfb\u4f53\u9a8c\u4e5f\u66f4\u597d\u3002<br \/>\n\u672c\u6587\u5730\u5740\uff1a<a href=\"https:\/\/www.zhangxinxu.com\/wordpress\/?p=9379\">https:\/\/www.zhangxinxu.com\/wordpress\/?p=9379<\/a><\/p>\n<p>\uff08\u672c\u7bc7\u5b8c\uff09<\/p>\n","protected":false},"excerpt":{"rendered":"<p><img decoding=\"async\" src=\"\/\/image.zhangxinxu.com\/image\/blog\/202004\/nice-cover.png\" width=\"160\" height=\"106\" alt=\"\u4e0d\u9519\u7684\u60c5\u4fa3\u5c01\u9762\u56fe\" class=\"alignright size-medium\" loading=\"lazy\" \/><\/p>\n<p>ES6 \u65b0\u589e\u4e86\u5f88\u591aMath\u65b9\u6cd5\uff0c\u6269\u5c55\u4e86\u4e00\u4e9bNumber\u65b0\u7279\u6027\uff0c\u672c\u6587\u5c31\u5bf9\u76f8\u5173\u77e5\u8bc6\u8fdb\u884c\u7684\u6574\u7406\u548c\u8bf4\u660e\uff0c\u5e0c\u671b\u53ef\u4ee5\u5bf9\u60a8\u7684\u5b66\u4e60\u6709\u6240\u5e2e\u52a9\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1284],"tags":[904,1602,1606,1603,1607,1599,1600,1601,1598,1597,1605,1604,334],"_links":{"self":[{"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/posts\/9379"}],"collection":[{"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/comments?post=9379"}],"version-history":[{"count":0,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/posts\/9379\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/media?parent=9379"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/categories?post=9379"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/tags?post=9379"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}