{"id":1448,"date":"2011-02-18T22:24:44","date_gmt":"2011-02-18T14:24:44","guid":{"rendered":"http:\/\/www.zhangxinxu.com\/wordpress\/?p=1448"},"modified":"2018-01-01T22:08:59","modified_gmt":"2018-01-01T14:08:59","slug":"%e7%bf%bb%e8%af%91-js%e8%a1%a8%e8%be%be%e5%bc%8f%e9%97%ad%e5%8c%85expression-closures%e7%9a%84%e8%bf%9b%e4%b8%80%e6%ad%a5%e4%ba%b2%e5%af%86%e6%8e%a5%e8%a7%a6","status":"publish","type":"post","link":"https:\/\/www.zhangxinxu.com\/wordpress\/2011\/02\/%e7%bf%bb%e8%af%91-js%e8%a1%a8%e8%be%be%e5%bc%8f%e9%97%ad%e5%8c%85expression-closures%e7%9a%84%e8%bf%9b%e4%b8%80%e6%ad%a5%e4%ba%b2%e5%af%86%e6%8e%a5%e8%a7%a6\/","title":{"rendered":"\u7ffb\u8bd1-js\u8868\u8fbe\u5f0f\u95ed\u5305(expression closures)\u7684\u8fdb\u4e00\u6b65\u4eb2\u5bc6\u63a5\u89e6"},"content":{"rendered":"

by zhangxinxu<\/a> from http:\/\/www.zhangxinxu.com<\/a>
\n\u672c\u6587\u5730\u5740\uff1ahttp:\/\/www.zhangxinxu.com\/wordpress\/?p=1448<\/a><\/p>\n

\n\t\u539f\u6587\u5730\u5740\uff1ahttp:\/\/perfectionkills.com\/a-closer-look-at-expression-closures\/<\/a>
\n \u539f\u6587\u4f5c\u8005\uff1akangax
\n \u7ffb\u8bd1\u7f16\u8f91\uff1a\u5f20\u946b\u65ed<\/a>\n<\/div>\n

\u4ee5\u4e0b\u4e3a\u7ffb\u8bd1\u5168\u6587\uff0c\u6709\u7f16\u8f91<\/p>\n

\u6700\u8fd1\u6211\u5728Firebug\u63a7\u5236\u53f0\u4e0a\u6298\u817e\u4e00\u4e9b\u4e1c\u897f\u7684\u65f6\u5019\u8bb0\u4f4f\u4e86\u8868\u8fbe\u5f0f\u95ed\u5305(expression closures)<\/a>\u3002\u8fd9\u662f\u4e2a\u9644\u52a0\u7684\u8bed\u8a00\uff0c\u5728Mozilla\u7684JavaScript 1.8<\/a>\u4e2d\u5f15\u5165\u3002<\/p>\n

MDC\u6293\u4f4f\u4e86\u8868\u8fbe\u5f0f\u95ed\u5305(expression closures)\u7684\u672c\u8d28\uff0c\u5e76\u5bf9\u5176\u8fdb\u884c\u4e86\u7b80\u660e\u7684\u89e3\u91ca\uff1a\/\/zxx:\u6211\u7422\u78e8\u7740\uff0c\u8fd9\u4e2aMDC\u5e94\u8be5\u662fMozilla Develope Center\uff0cMozilla\u5f00\u53d1\u4e2d\u5fc3\u3002<\/span><\/p>\n

\n\u8be5\u6dfb\u52a0\u53ea\u4e0d\u8fc7\u53ef\u4ee5\u8ba9\u7b80\u5355\u7684\u51fd\u6570\u901f\u5199\uff0c\u8ba9\u8bed\u8a00\u7c7b\u4f3c\u7684\u4e00\u4e2a\u5178\u578b\u7684\u03bb\u7b26\u53f7\u3002[\u2026]\u8be5\u8bed\u6cd5\u5141\u8bb8\u4f60\u4e0d\u8981\u82b1\u62ec\u53f7({})\u4ee5\u53ca”return”\u58f0\u660e\u2014\u2014\u4f7f\u5176\u66f4\u9690\u5f0f\u3002\u8fd9\u79cd\u4ee3\u7801\u4e66\u5199\u5f62\u5f0f\u9664\u4e86\u8bed\u6cd5\u6784\u6210\u4e0a\u8bb2\u77ed\u4e86\u5916\u6ca1\u6709\u5176\u4ed6\u7684\u597d\u5904\u3002\n<\/p><\/blockquote>\n

\u6b63\u597d\uff0c\u8fd9\u662f\u6211\u9700\u8981\u7684\u2014\u2014\u8fc5\u901f\u5730\u5c1d\u8bd5\u4e00\u4e9b\u4e1c\u897f\uff0c\u7f29\u77ed\u7684\u51fd\u6570\u8868\u8fbe\u5f0f\u4ee5\u8282\u7ea6\u6253\u5b57\u65f6\u95f4\u3002<\/p>\n

MDC\u540c\u65f6\u7ed9\u4e86\u4e2a\u4f8b\u5b50\uff0c\u5c55\u793a\u5982\u4f55\u4f7f\u7528\u8868\u8fbe\u5f0f\u95ed\u5305\u5199\u51fd\u6570\uff1a<\/p>\n

\n
\/\/ \u6b63\u5e38\u7684\u8bed\u6cd5<\/span>\nfunction() { return x * x }\n\n\/\/ \u8868\u8fbe\u5f0f\u95ed\u5305<\/span>\nfunction(x) x * x<\/pre>\n<\/div>\n
\u6b63\u5982\u4f60\u6240\u89c1\uff0c\u8868\u8fbe\u5f0f\u95ed\u5305\u9aa8\u5b50\u91cc\u5c31\u662f\u4e2a\u521b\u5efa\u66f4\u7b80\u5355\u51fd\u6570\u7684\u65b9\u5f0f\u3002\u6839\u636eMDC\uff0c\u8868\u8fbe\u5f0f\u95ed\u5305\u5141\u8bb8\u6211\u4eec\u628a\u51fd\u6570\u4f53\u4e2d\u7684\u82b1\u62ec\u53f7\u554a\u4ee5\u53ca”return”\u554a\u4ec0\u4e48\u7684\u5982\u64e6\u5c41\u80a1\u7eb8\u822c\u6254\u6389\u3002<\/p>\n
\u7136\u800c\uff0cMDC\u63d0\u4f9b\u7684\u5173\u4e8e\u8868\u8fbe\u5f0f\u95ed\u5305\u7684\u4fe1\u606f\u6bd4\u738b\u4e4b\u6da3\u6d41\u4f20\u4e0b\u6765\u7684\u8bd7\u8fd8\u5c11\uff0c\u4e8e\u662f\u6211\u5c31\u597d\u5947\u8868\u8fbe\u5f0f\u95ed\u5305\u7684\u5176\u4ed6\u4e00\u4e9b\u51fa\u8272\u7684\u7ec6\u8282\u3002\u5b83\u4eec\u662f\u4e0d\u662f\u53ea\u80fd\u7528\u6765\u521b\u5efa\u51fd\u6570\u8868\u8fbe\u5f0f\uff1f\u51fd\u6570\u58f0\u660e\u600e\u4e48\u6837\uff1f\u5df2\u547d\u540d\u51fd\u6570\u8868\u8fbe\u5f0f\u53c8\u5982\u4f55\uff1f\u662f\u5426function() ...<\/code>\u603b\u662f\u548cfunction(){return ...}<\/code>\u4e00\u6837\uff0c\u800c\u4e0e ...<\/code>(\u51fd\u6570\u4f53)\u65e0\u5173\uff1fMDC\u6240\u8c08\u5230\u7684\u201c\u7b80\u5355\u51fd\u6570\u201d\u5230\u5e95\u6307\u4ec0\u4e48\uff1f<\/p>\n
\u4e0a\u9762\u7684\u95ee\u9898\u4e00\u4e2a\u4e5f\u6ca1\u6709\u7b54\u6848\uff0c\u6240\u4ee5\u6211\u51b3\u5b9a\u505a\u4e2a\u5feb\u901f\u7684\u7814\u7a76\uff0c\u7ed9\u8fd9\u4e2a\u65f6\u9ae6\u7684\u8bed\u8a00\u52a0\u70b9\u6df1\u5ea6\u3002\u4e0b\u9762\u7684\u5c31\u662f\u6211\u7684\u53d1\u73b0\uff1b\u4f60\u4f1a\u53d1\u73b0\u67d0\u4e9b\u884c\u4e3a\u4e0d\u662f\u90a3\u4e48\u660e\u663e\u3002<\/p>\n
\u8ba9\u4ee3\u7801\u81ea\u5df1\u8bf4\u8bdd\uff0c\u8fd9\u91cc\u662f\u4e00\u4e2a\u7b80\u5355\u7684\u6d4b\u8bd5\u4e4b\u540e\u95ee\u9898\u6e05\u5355\uff0c\u8bd5\u56fe\u56de\u7b54\u8fd9\u4e9b\u95ee\u9898\u3002\u4e0b\u9762\u7684\u7b80\u77ed\u53d9\u8ff0\u7684\u53d1\u73b0\u4f60\u53ef\u4ee5\u968f\u610f\u8df3\u8fc7\u3002<\/p>\n
\u6d4b\u8bd5(Test)<\/h3>\n
    \n
  1. \n
    \u662f\u5426\u8868\u8fbe\u5f0f\u95ed\u5305\u53ef\u4ee5\u7528\u6765\u521b\u5efa\u51fd\u6570\u58f0\u660e\uff08\u800c\u4e0d\u4ec5\u4ec5\u662f\u51fd\u6570\u8868\u8fbe\u5f0f\uff09\uff1f<\/p>\n
    \u7b54\u6848\u662f\uff1a\u662f\u7684\u3002<\/p>\n
    \n
    function f(x, y) x + y\ntypeof f; \/\/ \"function\"<\/span><\/pre>\n<\/div>\n
    \u4e0a\u9762\u7684\u6d4b\u8bd5\u4ee3\u7801\uff0c\u6b63\u5e38\u7684\u58f0\u660e\u5e94\u8be5\u662f\uff1atypeof(f);<\/code>\uff0c\u800c\u73b0\u5728\u5c31\u662ftypeof f<\/code>\uff0c\u6d4b\u8bd5\u7ed3\u679c\u663e\u793a\u662f\u652f\u6301\u7684\u3002<\/p>\n
    \u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0e\u51fd\u6570\u58f0\u660e\u6d4b\u8bd5demo<\/a><\/p>\n
    <\/div>\n
    \u70b9\u51fbdemo\u9875\u9762\u4e2d\u7684\u201c\u70b9\u51fb\u6211\u5f39\u51fa\u7ed3\u679c\u201d\u6309\u94ae\u67e5\u770b\u6548\u679c\uff0c\u5728firefox\u6d4f\u89c8\u5668\u4e2d\u53ef\u4ee5\u770b\u5230\u5982\u4e0b\u7684\u5f39\u51fa\u6846\uff1a<\/p>\n
    \"\u8868\u8fbe\u5f0f\u95ed\u5305\u6d4b\u8bd5\u5f39\u51fa\u7ed3\u679c<\/div>\n
    \u56e0\u4e3a\u8868\u8fbe\u5f0f\u95ed\u5305\u662fmozilla\u7684\u4e1c\u897f\uff0c\u6240\u4ee5\u76ee\u524d\u5728\u8bf8\u5982IE\/Chrome\u6d4f\u89c8\u5668\u4e0b\u662f\u6ca1\u6709\u6548\u679c\u7684\u3002\u706b\u72d0\u6d4f\u89c8\u5668\u4e0b\u76f4\u63a5\u4e0b\u9762\u4ee3\u7801\u5c31\u6709\u6548\u679c\u4e86\uff1a<\/p>\n
    \n
    <script>\nfunction f(x, y) x + y\nalert(typeof f); \n<\/script><\/pre>\n<\/div>\n
    \u4f46\u662f\u5982\u679c\u5c31\u4e0a\u9762\u5149\u79c3\u79c3\u7684\u4ee3\u7801\u7684\u8bdd\uff0c\u5176\u4ed6\u6d4f\u89c8\u5668\u4e0b\u4f1a\u662f\u62a5\u9519\u7684\uff0c\u4e3a\u4e86\u53cb\u597d\u5176\u4ed6\u6d4f\u89c8\u5668\uff0c\u53ef\u4ee5\u7ed9javascript\u4ee3\u7801\u6dfb\u52a0\u7248\u672c\u8bf4\u660e\uff0c\u5c31\u5728type\u5c5e\u6027\u4e2d\uff0c\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n
    \n
    <script type=\"application\/javascript;version=1.8\">\nfunction f(x, y) x + y\nalert(typeof f); \n<\/script><\/pre>\n<\/div>\n<\/li>\n
  2. \n
    \u5df2\u547d\u540d\u51fd\u6570\u8868\u8fbe\u5f0f\u53c8\u5982\u4f55\uff1f<\/p>\n
    \u7ed3\u679c\u662f\uff1a\u652f\u6301\u3002<\/p>\n
    \n
    typeof (function f(x, y) x + y); \/\/ \"function\"<\/span><\/pre>\n<\/div>\n
    \u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0e\u5df2\u547d\u540d\u51fd\u6570\u8868\u8fbe\u5f0f\u6d4b\u8bd5demo<\/a><\/p>\n
    \u6548\u679c\u4ee5\u53ca\u6ce8\u610f\u4e8b\u9879\u4e0e\u4e0a\u9762\u4e00\u81f4\u3002<\/p>\n<\/li>\n
  3. \n
    \u8868\u8fbe\u5f0f\u95ed\u5305\u5982\u4f55\u5f71\u54cd\u51fd\u6570\u8868\u793a\uff1f<\/p>\n
    \u5c31\u8ddf\u5e73\u5e38\u4e00\u6837\uff0c\u5c31\u662f\u4e0d\u5305\u542b\u82b1\u62ec\u53f7\u4ee5\u53ca”return”\u5173\u952e\u5b57\u3002<\/p>\n
    \n
    String(function (x) x + x ); \/\/ \"function (x) x + x;\"<\/span><\/pre>\n<\/div>\n
    \u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0e\u51fd\u6570\u8868\u793a\u6d4b\u8bd5demo<\/a><\/p>\n
    \u5728FireFox\u6d4f\u89c8\u5668\u4e0b\u70b9\u51fb\u9875\u9762\u4e0a\u7684\u6309\u94ae\u540e\u7684\u6548\u679c\u5982\u4e0b\uff1a<\/p>\n
    \"\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0e\u51fd\u6570\u8868\u793a\u6d4b\u8bd5\u7ed3\u679c<\/div>\n<\/li>\n
  4. \n
    \u5173\u4e8e\u975e\u6807\u51c6\u7684”name”\u5c5e\u6027\uff1f<\/p>\n
    \u7ed3\u679c\uff1a\u5982\u9884\u671f\u5de5\u4f5c\uff01<\/p>\n
    \n
    function foo(x, y) x + y;\nfoo.name; \/\/ \"foo\"<\/span><\/pre>\n<\/div>\n
    \u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0e\u975e\u6807\u51c6name\u5c5e\u6027\u6d4b\u8bd5demo<\/a><\/p>\n
    \u7ed3\u679c\u5982\u4e0b\u56fe\uff1a<\/p>\n
    \"\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0e\u975e\u6807\u51c6name\u5c5e\u6027\u6d4b\u8bd5\u7ed3\u679c<\/div>\n<\/li>\n
  5. \n
    \u5373\u65f6\u5e94\u7528\u51fd\u6570\u8868\u8fbe\u5f0f\u600e\u4e48\u6837\uff1f<\/p>\n
    \u7ed3\u679c\u662f\uff1a\u5de5\u4f5c\u826f\u597d\u3002<\/p>\n
    \n
    (function(x, y) x + y)(1, 2); \/\/ 3<\/span><\/pre>\n<\/div>\n
    \u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0e\u5373\u65f6\u5e94\u7528\u51fd\u6570\u8868\u8fbe\u5f0f\u6d4b\u8bd5demo<\/a><\/p>\n
    \u7ed3\u679c\u5982\u4e0b\u56fe\uff1a<\/p>\n
    \"\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0e\u5373\u65f6\u5e94\u7528\u51fd\u6570\u8868\u8fbe\u5f0f\u6d4b\u8bd5\u7ed3\u679c<\/div>\n<\/li>\n
  6. \n
    \u6ca1\u6709\u62ec\u53f7\u5305\u88f9\u7684\u5373\u65f6\u5e94\u7528\u51fd\u6570\u8868\u8fbe\u5f0f\uff1f<\/p>\n
    \u7ed3\u679c\uff1a\u554a\u54e6\uff0c\u6709\u70b9\u5c0f\u7599\u7629<\/p>\n
    \n
    var f1 = (function(x, y) x + y)(1, 2);\nvar f2 = function(x, y) x + y (1, 2);\n \nf1; \/\/ 3<\/span>\nf2; \/\/ function(x, y) x + y(1, 2)<\/span><\/pre>\n<\/div>\n
    \u6b63\u5982\u4f60\u6240\u770b\u5230\u7684\uff0cx + y<\/code>\u4e4b\u540e\u7684(1, 2)<\/code>\u5b9e\u9645\u4e0a\u88ab\u5f53\u505a\u5185\u90e8\u7684\u8868\u8fbe\u5f0f\u4e86\uff0c\u800c\u4e0d\u662f\u5e94\u7528\u5728\u5916\u90e8\u51fd\u6570\u4e0a\u3002x + y(1, 2)<\/code>\u5f53\u505a\u4e00\u4e2a\u6574\u4f53\u5f53\u505af2<\/code>\u7684\u8fd4\u56de\u503c\u4e86\u3002\u8fd9\u662f\u660e\u786e\u53ef\u4ee5\u77e5\u9053\u7684\u3002<\/p>\n
    \u5982\u679c\u60a8\u624b\u5934\u4e0a\u7684\u6b63\u662fFirefox\u6d4f\u89c8\u5668\uff0c\u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0e\u65e0\u62ec\u53f7\u5305\u88f9\u7684\u5373\u65f6\u5e94\u7528\u51fd\u6570\u8868\u8fbe\u5f0fdemo<\/a><\/p>\n<\/li>\n
  7. \n
    \u8868\u8fbe\u5f0f\u95ed\u5305\u5728ECMAScript 5\u8bbf\u95ee\u8bed\u6cd5\u4e0b\u662f\u5426\u8d77\u4f5c\u7528\uff08\u5148\u8bd5\u8bd5get\u65b9\u6cd5\uff09\uff1f<\/p>\n
    \u7ed3\u679c\u662f\uff1a\u8d77\u4f5c\u7528\u6ef4\u3002<\/p>\n
    \n
    var obj = ({ get foo() 1 });\nobj.foo; \/\/ 1<\/span><\/pre>\n<\/div>\n
    \u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0eES5\u8bbf\u95ee\u8bed\u6cd5\u6d4b\u8bd5demo<\/a><\/p>\n
    \u7ed3\u679c\u5982\u4e0b\u56fe\uff1a<\/p>\n
    \"\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0eES5\u8bbf\u95ee\u8bed\u6cd5\u6d4b\u8bd5\"<\/div>\n
    \u5982\u679c\u60a8\u770b\u5230\u4e0b\u9762\u7684\u6587\u5b57\uff0c\u53ef\u80fd\u662f\u7531\u4e8e\u5728\u5176\u4ed6\u7f51\u7ad9\u6216\u662fRSS\u4e2d\u9605\u8bfb\u672c\u6587\uff0c\u672c\u6587\u539f\u5730\u5740\uff1ahttp:\/\/www.zhangxinxu.com\/wordpress\/?p=1448<\/a>\uff0c\u672c\u6587\u4f5c\u8005\uff1a\u5f20\u946b\u65ed<\/a>\uff0c\u6765\u81ea\u5f20\u946b\u65ed-\u946b\u7a7a\u95f4-\u946b\u751f\u6d3b\uff0c\u8bbf\u95ee\u539f\u51fa\u5904\u66f4\u591a\u4f18\u79c0\u6280\u672f\u6587\u7ae0\u3002<\/em><\/div>\n<\/li>\n
  8. \n
    \u90a3\u4e48set\u65b9\u6cd5\u5462\uff1f<\/p>\n
    \u7b54\u6848\u662f\uff1a\u540c\u6837\u53ef\u4ee5\u3002<\/p>\n
    \n
    var _x;\nvar obj = ({ set foo(x) _x = x });\nobj.foo = 5;\n \n_x; \/\/ 5<\/pre>\n<\/div>\n
    \u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0eES5 set\u8bed\u6cd5\u6d4b\u8bd5demo<\/a><\/p>\n
    \u7ed3\u679c\u70b9\u51fbdemo\u9875\u9762\u7684\u6d4b\u8bd5\u6309\u94ae\uff0c\u5728\u6211\u7684\u706b\u72d0\u6d4f\u89c8\u5668\u4e0b\u5f39\u51fa\u7ed3\u679c\u662f”5<\/code>“\u3002<\/p>\n<\/li>\n
  9. \n
    \u8981\u662f\u53cc\u7ba1\u9f50\u4e0b\u5462\uff1f<\/p>\n
    \u7ed3\u679c\uff1a\u90fdok\uff01\u6069\uff0c\u6ca1\u7406\u7531\u4e0dok\u554a~~<\/p>\n
    \n
    var _x = '\u521d\u59cb\u503c';\nvar obj = ({ get foo() _x, set foo(x) _x = x });\nobj.foo; \/\/ '\u521d\u59cb\u503c'<\/span>\n\nobj.foo = '\u91cd\u7f6e\u503c';\nobj.foo; \/\/ '\u91cd\u7f6e\u503c'<\/span><\/pre>\n<\/div>\n
    \u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0eES5 set\/get\u53cc\u7ba1\u9f50\u4e0b\u6d4b\u8bd5demo<\/a><\/p>\n
    \u70b9\u51fb\u6d4b\u8bd5\u6309\u94ae\u540e\uff0c\u8fde\u7eed\u5f39\u51fa\u4e0b\u56fe\u6240\u793a\u4e24\u5f39\u6846\uff1a<\/p>\n
    <\/div>\n<\/li>\n
  10. \n
    \u6211\u4eec\u53ef\u4ee5\u7528\u9017\u53f7\u6df7\u6dc6\u5206\u6790\u5668\uff1f<\/p>\n
    \u7b54\u6848\u662f\uff1a\u662f\u7684\u3002<\/p>\n
    \n
      ({ set foo(x) bar = 1, baz = 2 }); \/\/ \u89e3\u6790\u9519\u8bef<\/span><\/pre>\n<\/div>\n
    \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u6211\u4eec\u53ef\u80fd\u5e0c\u671bbar = 1, baz = 2<\/code>\u4f5c\u4e3a\u51fd\u6570\u5185\u90e8\u7684\u4e00\u4e2a\u8868\u8fbe\u5f0f\uff0c\u7136\u800c\uff0c\u9017\u53f7\u88ab\u89e3\u91ca\u6210\u4e86\u5bf9\u8c61\u521d\u59cb\u5316\u7684\u4e00\u90e8\u5206\u3002\u5f53\u7136\uff0c\u5305\u88f9\u4e00\u526f\u62ec\u53f7\u53ef\u4ee5\u89e3\u51b3\u5b57\u95ee\u9898\u3002<\/p>\n
    \n
    ({ set foo(x) (bar = 1, baz = 2) });<\/pre>\n<\/div>\n<\/li>\n
  11. \n
    \u8bed\u53e5\u662f\u5426\u5141\u8bb8\u5b58\u5728\u4e8e\u901a\u8fc7\u8868\u8fbe\u5f0f\u95ed\u5305\u521b\u5efa\u51fd\u6570\u7684\u51fd\u6570\u4f53\u4e2d\uff1f<\/p>\n
    \u7b54\u6848\u662f\uff1aNo!<\/p>\n
    \n
    var f = function() if (true) \"foo\"; \/\/ \u9519\u8bef<\/span><\/pre>\n<\/div>\n
    \u8fd9\u4e2a\u76f8\u5f53\u5bb9\u6613\u7406\u89e3\u3002\u8868\u8fbe\u5f0f\u95ed\u5305\u4e2d\uff0cfunction()<\/code>\u540e\u9762\u8ddf\u7740\u7684\u8868\u8fbe\u5f0f\u76f4\u63a5\u88ab\u5f53\u505a\u8981\u88abreturn<\/code>\u8bed\u53e5\u540e\u9762\u7684\u4e1c\u897f\u7ed9return\u6389\u4e86\u3002\u663e\u7136\uff0creturn<\/code>\u8bed\u53e5\u662f\u4e0d\u80fd\u8fd4\u56de\u5176\u4ed6\u8bed\u53e5\u7684\uff0c\u5c31\u662f\u8bf4return if (true) \"foo\";<\/code>\u662f\u884c\u4e0d\u901a\u7684\u3002\u4e0d\u8fc7\u5e78\u8fd0\u7684\u662f\uff0c\u6709\u4e2a\u53eb\u505a\u4e09\u5143\u8fd0\u7b97\u7684\u4e1c\u897f\u53ef\u4ee5\u597d\u597d\u5b89\u629a\u8fd9\u91cc\u7684\u5c0f\u9519\u8bef\uff1a<\/p>\n
    \n
    var f = function() someCondition ? \"foo\" : \"bar\";<\/pre>\n<\/div>\n<\/li>\n
  12. \n
    \u901a\u8fc7\u8868\u8fbe\u5f0f\u95ed\u5305\u521b\u5efa\u7684\u51fd\u6570\u4f53\u662f\u5426\u53ef\u4ee5\u5ffd\u7565\uff1f<\/p>\n
    (*^__^*) \u563b\u563b\u2026\u2026\uff0c\u7b54\u6848\u662f\uff1a\u95e8\u90fd\u6ca1\u6709\uff01<\/p>\n
    \n
      function f() \/\/ \u9519\u8bef<\/span><\/pre>\n<\/div>\n
    \u4f60\u53ef\u80fd\u4f1a\u60f3\u554a\uff0c\u8fd9function f()<\/code>\u5e94\u8be5\u7b49\u540c\u4e8efunction f(){ return }<\/code>\u3002\u4f46\u662f\uff0c\u4e0d\u662f\u6ef4\uff0c\u8fd9\u91cc\u7a7a\u51fd\u6570\u4f53\u65f6\u4e0d\u5141\u8bb8\u7684\u3002\u81f3\u4e8e\u4e3a\u4ec0\u4e48\u4f1a\u8fd9\u6837\u8fd8\u4e0d\u662f\u5f88\u6e05\u695a\u3002\u89e3\u6790\u590d\u6742\uff0c\u9519\u4e71\u5982\u9ebb\uff1f\u6216\u8bb8\u5427\u3002<\/p>\n<\/li>\n
  13. \n
    \u5982\u679c\u4e0d\u6b62\u4e00\u4e2a\u8868\u8fbe\u5f0f\u4f1a\u600e\u6837\u5462\uff1f<\/p>\n
    \u7ed3\u679c\u662f\uff1a\u53ea\u6709\u7b2c\u4e00\u4e2a\u88ab\u5f53\u505a\u67f4\u6cb9\u6765\u70e7\u3002<\/p>\n
    \n
    function f() alert(\"\u7b2c\u4e00\u4e2a\u8bed\u53e5\"); alert(\"\u7b2c\u4e8c\u4e2a\u8bed\u53e5\"); alert(\"\u7b2c\u4e09\u4e2a\u8bed\u53e5\"); \/\/ \u5f39\u51fa \"\u7b2c\u4e8c\u4e2a\u8bed\u53e5\"\u548c\"\u7b2c\u4e09\u4e2a\u8bed\u53e5\"<\/span><\/pre>\n<\/div>\n
    \u4e0a\u9762\u7684\u8bed\u53e5\u88ab\u89e3\u6790\u6210\u4e86\uff1a<\/p>\n
    \n
    function f() { return alert(\"\u7b2c\u4e00\u4e2a\u8bed\u53e5\"); } alert(\"\u7b2c\u4e8c\u4e2a\u8bed\u53e5\"); alert(\"\u7b2c\u4e09\u4e2a\u8bed\u53e5\");<\/pre>\n<\/div>\n
    \u53ea\u6709\u7b2c\u4e00\u4e2a\u8868\u8fbe\u5f0f\u4f5c\u4e3a\u4e86\u8868\u8fbe\u5f0f\u95ed\u5305\u7684\u71c3\u6599\u4f7f\u7528\u4e86\u3002<\/p>\n
    \u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0e\u591a\u8868\u8fbe\u5f0f\u6d4b\u8bd5demo<\/a><\/p>\n<\/li>\n
  14. \n
    \u5206\u53f7\u81ea\u52a8\u63d2\u5165\u89c4\u5219\u600e\u4e48\u6837\u5462\uff1f<\/p>\n
    \u7b54\u6848\u662f\uff1a\u89c4\u5219\u4e00\u81f4\u3002<\/p>\n
    \n
    function foo(x) x\n(function() {\n\/* ... *\/<\/span>\n})()\n\nfoo; \/\/ function foo(x) x(function(){ \/* ... *\/})()<\/span><\/pre>\n<\/div>\n
    \u8fd9\u662f\u4e2a\u7ecf\u5178\u7684\u5206\u53f7\u81ea\u52a8\u63d2\u5165\u5b9e\u4f8b\u2014\u2014\u51fd\u6570\u58f0\u660e\u5728\u65b0\u7684\u4e00\u884c\u540c\u65f6\u5728\u8868\u8fbe\u5f0f\u7684\u540e\u9762\u51fa\u73b0\u7684\u5947\u602a\u8868\u73b0\u3002\u8fd9\u91cc\u89c4\u5219\u4e00\u81f4\uff0cfoo<\/code>\u51fd\u6570\uff08\u5373\u4f7f\u662f\u8868\u8fbe\u5f0f\u95ed\u5305\uff09\u4e5f\u4ee5\u51fd\u6570\u4f53x(function(){})()<\/code>\u800c\u4e0d\u662fx<\/code>\u7ed3\u675f\u3002<\/p>\n
    \u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0e\u5206\u53f7\u81ea\u52a8\u63d2\u5165\u89c4\u5219\u6d4b\u8bd5demo<\/a><\/p>\n
    \u7ed3\u679c\u5982\u4e0b\u56fe\uff1a<\/p>\n
    <\/div>\n<\/li>\n
  15. \n
    “{“\u662f\u5f53\u505a\u58f0\u660e\u5757\u8fd8\u662f\u5bf9\u8c61\u5b57\u9762\u91cf\uff1f<\/p>\n
    \u7ed3\u679c\u662f\uff1a\u8bed\u53e5\u5757\u3002\u6574\u4f53\u751f\u4ea7\u57fa\u672c\u4e0a\u7b26\u5408\u5e38\u89c4\u7684\u51fd\u6570\u8bed\u6cd5\u3002<\/p>\n
    \n
    function foo(x) { top: 0, left: 0 } \/\/ \u8bed\u6cd5\u9519\u8bef<\/span><\/pre>\n<\/div>\n
    \u4f60\u53ef\u80fd\u4f1a\u60f3\uff0cfunction foo(x) { top: 0, left: 0 }<\/code>\u5e94\u8be5\u88ab\u89e3\u6790\u6210function foo(x) { return { top: 0, left: 0 } }<\/code>\uff0c\u4f46\u662f\u8fd9\u91cc\u201c\u6b63\u5e38\u201d\u89e3\u6790\u89c4\u5219\u5148\u6267\u884c\uff0c\u800cfunction foo(x) { top: 0, left: 0 }<\/code>\u56de\u5bfc\u81f4\u9519\u8bef\uff0c\u82b1\u62ec\u53f7{<\/code>\u548c}<\/code>\u88ab\u89e3\u6790\u6210\u4e86\u51fd\u6570\u4f53\uff0c\u800ctop: 0, left: 0<\/code>\u88ab\u5f53\u505a\u51fd\u6570\u4f53\u91cc\u9762\u7684\u5185\u5bb9\u4e86\u3002<\/p>\n<\/li>\n
  16. \n
    \u5982\u679c\u662f\u4e2a\u8868\u8fbe\u5f0f\u5462\uff1f<\/p>\n
    \u7ed3\u679c\u4e0e\u4e0a\u9762\u4e00\u6837\u3002<\/p>\n
    \n
      (function(x, y) { left: x, top: y }) \/\/ \u8bed\u6cd5\u9519\u8bef<\/span><\/pre>\n<\/div>\n
    \u4f60\u5fc5\u987b\u5c0f\u5fc3\u5730\u7528\u62ec\u53f7\u5305\u88f9\u8fd4\u56de\u7684\u5bf9\u8c61\uff0c\u4e3a\u7684\u662f\u82b1\u62ec\u53f7\u4e0d\u4f1a\u88ab\u8ba4\u4e3a\u662f\u51fd\u6570\u751f\u6210\u7684\u4e00\u90e8\u5206\u3002\u5728\u672c\u4f8b\u4e2d\uff0cleft: x, top: y<\/code>\u5bfc\u81f4\u4e86\u4e2a\u9519\u8bef\u3002\u4f46\u662f\uff0c\u5982\u679c\u8fd4\u56de\u7684\u5bf9\u8c61\u53ea\u5305\u542b\u4e00\u4e2a\u503c\uff0c\u6216\u8005\u751a\u81f3\u6ca1\u6709\u503c\uff0c\u5219\u4f1a\u6709\u7c7b\u4f3c\u4e0b\u9762\u7684\u610f\u60f3\u4e0d\u5230\u7684\u884c\u4e3a\u8868\u73b0\uff1a<\/p>\n
    \n
    (function() { x: 1 } )(); \/\/ \u8fd4\u56de \"undefined\"<\/span>\n(function() ({ x: 1 }) )(); \/\/ \u8868\u8fbe\u5f0f\u95ed\u5305; \u8fd4\u56de\u5e26\u6709x=1\u7684\u5bf9\u8c61<\/span>\n\n(function() {} )(); \/\/ \u8fd4\u56de \"undefined\"<\/span>\n(function() ({}) )(); \/\/ \u8868\u8fbe\u5f0f\u95ed\u5305; returns \u5bf9\u8c61<\/span>\n        <\/pre>\n<\/div>\n<\/li>\n
  17. \n
    \u662f\u5426\u53ef\u4ee5\u8ba9\u51fd\u6570\u660e\u786e\u4e25\u683c\uff1f<\/p>\n
    \u7b54\u6848\u662f\uff1a\u4e0d\u884c\u7684\uff01<\/p>\n
    \n
    function foo(x, y) \"use strict\"; 1 + 1;\ntypeof foo(); \/\/ \"string\" (\u800c\u4e0d\u662f \"number\")<\/span><\/pre>\n<\/div>\n
    \u663e\u7136\u6ca1\u8d77\u4f5c\u7528\u3002\u672c\u60f3\u4f7f\u7528\u4e25\u683c\u6307\u4ee4(use strict)\u8ba9\u51fd\u6570\u884c\u4e3a\u8868\u73b0\u5f97\u8ddfECMAScript 5\u4e2d\u7684\u4e25\u683c\u6a21\u5f0f\u89c4\u5219\u4e00\u6837\uff0c\u7136\u800c\u6ca1\u6709\u4efb\u4f55\u7279\u6b8a\u7684\u8868\u73b0\u3002”use strict”\u88ab\u76f4\u63a5\u5f53\u505a\u4e86\u5b57\u7b26\u4e32\u5b57\u9762\u91cf\u3002\u4e8e\u662f\uff0c\u4e0a\u9762\u7684\u4ee3\u7801\u5c31\u76f4\u63a5\u88ab\u89e3\u6790\u6210\u4e86function foo(){ return \"use strict\"; }<\/code>\uff0c\u7136\u540e\u540e\u9762\u5c31\u662f\u65e0\u6b62\u5c3d\u76841 + 1<\/code>\u8bed\u53e5\u3002<\/p>\n
    \u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a\u8868\u8fbe\u5f0f\u95ed\u5305\u4e0e\u4e25\u683c\u6a21\u5f0f\u6d4b\u8bd5demo<\/a><\/p>\n
    \u7ed3\u679c\u5982\u4e0b\u622a\u56fe\uff08\u622a\u81ea FireFox 3.6\uff09\uff1a<\/p>\n
    <\/div>\n
    \u539f\u4f5c\u8005\u4e5f\u63d0\u4f9b\u4e86\u4e0a\u9762\u5c0f\u4f8b\u5b50\u7684\u4e00\u7cfb\u5217\u6d4b\u8bd5\u7ed3\u679c\uff0c\u60a8\u53ef\u4ee5\u70b9\u51fb\u8fd9\u91cc<\/a>\u67e5\u770b\u3002<\/p>\n<\/li>\n<\/ol>\n
    \u4e3b\u8981\u7279\u5f81<\/h3>\n
    \u6069\uff0c\u771f\u662f\u6709\u610f\u601d\u3002\u73b0\u5728\u603b\u7ed3\u4e0b\u4e00\u4e9b\u4e3b\u8981\u7279\u5f81\uff1a<\/p>\n
      \n
    1. \u51fd\u6570\u4f53\u9700\u4e00\u76f4\u5b58\u5728<\/li>\n
    2. \u53ea\u6709\u7b2c\u4e00\u4e2a\u8868\u8fbe\u5f0f\u4f1a\u88ab\u5f53\u505areturn\u8bed\u53e5<\/li>\n
    3. \u51fd\u6570\u58f0\u660e\u548c\u51fd\u6570\u8868\u8fbe\u5f0f\uff08\u663e\u793a\u547d\u540d\u8fd8\u662f\u533f\u540d\u7684\uff09\u90fd\u53ef\u4ee5\u7528\u6765\u88ab\u66ff\u6362<\/li>\n
    4. function idopt<\/sub> (argsopt<\/sub>) expr<\/code>\u4e0d\u5b8c\u5168\u7b49\u4e8efunction idopt<\/sub> (argsopt<\/sub>) { return expr }<\/code>\uff08\u4f9d\u8d56\u4e8e\u4e0a\u4e0b\u6587\uff09<\/li>\n
    5. \u4f18\u5148\u5e94\u7528\u7684\u8868\u8fbe\u5f0f\u4e0d\u660e\u663e\u3002\u4f8b\u5982\uff1a(function()x+y)()<\/code> vs. function()x+y()<\/code>\u3002<\/li>\n<\/ol>\n
      \u5b9e\u8df5\uff1f<\/h3>\n
      \u636e\u6211\u6240\u77e5\uff0c\u76ee\u524d\u4ec5\u57fa\u4e8eMozilla\u7684\u6d4f\u89c8\u5668\u652f\u6301\u8868\u8fbe\u5f0f\u95ed\u5305\uff0c\u5176\u4e5f\u4e0d\u88ab\u8bf8\u5982Google Closure Compiler\u6216\u662fYUI Compressor\u8fd9\u6837\u7684\u5de5\u5177\u652f\u6301\uff0c\u8fd9\u4e9b\u52bf\u5fc5\u589e\u52a0\u4e86\u5176\u5728\u5b9e\u9645\u9879\u76ee\u5e94\u7528\u4e2d\u7684\u6311\u6218\u3002<\/p>\n
      \u76ee\u524d\u8fd8\u4e0d\u6e05\u695a\u662f\u5426\u6709\u66f4\u591a\u7684\u5de5\u5177\u4f1a\u52a0\u5165mozilla\uff0c\u6dfb\u52a0\u5bf9\u8fd9\u79cd\u7b80\u5199\u7684\u652f\u6301\u3002\u662f\u5426\u5176\u53ef\u4ee5\u4f5c\u4e3a\u548c\u8c10\u4e4b\u8def(road to Harmony)<\/a>\u5b9e\u9a8c\u7684\u4e00\u90e8\u5206\uff08\u4ee5\u53ca\u5176\u51fd\u6570\u7f29\u5199\u8bed\u6cd5<\/a>\uff09\u2014\u2014\u4e0b\u4e00\u4e2aECMAScript\u8bed\u8a00\u7248\u672c\uff1f\u4f60\u662f\u5426\u5df2\u7ecf\u5728\u4f60\u7684\u5de5\u4f5c\/\u5b9e\u9a8c\u4e2d\u4f7f\u7528\u8868\u8fbe\u5f0f\u95ed\u5305\uff0c\u6216\u8005\u53ef\u80fd\u8ba1\u5212\u4f7f\u7528\uff1f\u4f60\u4f1a\u6539\u53d8\u4ed6\u4eec\u7684\u884c\u4e3a\u5417\uff1f<\/p>\n
      \u4ee5\u4e0a\u4e3a\u7ffb\u8bd1\u5168\u6587<\/p>\n
      \u5927\u7ed3\u5c40<\/h3>\n
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