{"id":2204,"date":"2012-02-15T22:41:46","date_gmt":"2012-02-15T14:41:46","guid":{"rendered":"http:\/\/www.zhangxinxu.com\/wordpress\/?p=2204"},"modified":"2018-01-02T01:21:37","modified_gmt":"2018-01-01T17:21:37","slug":"responsive-images-introduce","status":"publish","type":"post","link":"https:\/\/www.zhangxinxu.com\/wordpress\/2012\/02\/responsive-images-introduce\/","title":{"rendered":"\u70ed\u95e8\uff1a\u54cd\u5e94\u56fe\u7247(Responsive Images)\u6280\u672f\u7b80\u4ecb"},"content":{"rendered":"<p>by <a href=\"http:\/\/www.zhangxinxu.com\/\">zhangxinxu<\/a> from <a href=\"http:\/\/www.zhangxinxu.com\/\">http:\/\/www.zhangxinxu.com<\/a><br \/>\n\u672c\u6587\u5730\u5740\uff1a<a href=\"http:\/\/www.zhangxinxu.com\/wordpress\/?p=2204\">http:\/\/www.zhangxinxu.com\/wordpress\/?p=2204<\/a><\/p>\n<h3>\u4e00\u3001\u5f00\u95e8\u89c1\u5c71<\/h3>\n<p>\u54cd\u5e94\u56fe\u7247\u6280\u672f\u53ef\u4ee5\u8bf4\u662f<a href=\"http:\/\/www.zhangxinxu.com\/wordpress\/?p=1937\">\u54cd\u5e94\u5e03\u5c40<\/a>\u884d\u751f\u51fa\u6765\u7684\u4e00\u4e2a\u5c0f\u5206\u652f\u3002\u8bf4\u767d\u4e86\uff0c\u5c31\u662f\u4e0d\u540c\u663e\u793a\u5668\u5bbd\u5ea6\u4e0b\u8c03\u7528\u4e0d\u540c\u7684\u56fe\u7247\u3002<\/p>\n<p>\u8fd9\u73a9\u610f\uff0c\u6700\u8fd1\u5728\u56fd\u5916\u8ba8\u8bba\u5f88\u706b\uff0c\u6709\u51e0\u79cd\u4e0d\u540c\u7684\u5b9e\u73b0\u65b9\u6cd5\uff0c\u4f46\u90fd\u5e76\u4e0d\u590d\u6742\u3002<\/p>\n<h3>\u4e8c\u3001Cookie + Server\u5b9e\u73b0<\/h3>\n<p>github\u4e0a\u6709\u8be5\u6280\u672f<a href=\"https:\/\/github.com\/filamentgroup\/Responsive-Images\/tree\/cookie-driven\">\u4ecb\u7ecd<\/a>\u3002\u8be5\u6280\u672f\u9700\u8981Javascript\u4ee5\u53ca\u540e\u53f0\u7a0b\u5e8f\u7684\u914d\u5408\u3002<\/p>\n<p>\u52a0\u8f7d\u9700\u8981\u7684JS\u6587\u4ef6<a href=\"http:\/\/filamentgroup.com\/examples\/responsive-images-new\/responsive-images.js\">responsive-images.js<\/a>, \u8be5JS\u6587\u4ef6\u4e3a\u83b7\u53d6\u5f53\u524d\u7528\u6237\u663e\u793a\u5668\u5bbd\u5ea6\uff0c\u7136\u540e\u6839\u636e\u5bbd\u5ea6\u503c\u5927\u5c0f\u51b3\u5b9a\u56fe\u7247\u662f\u5c0f(small)\u5462\uff0c\u4e2d\u7b49(medium)\u5462\u8fd8\u662f\u5927(large)\uff0c\u7136\u540e\u5199\u5165\u5bf9\u5e94\u7684Cookie.<\/p>\n<p>\u4e0b\u9762\u5c31\u662f\u670d\u52a1\u5668\u7aef\u4e8b\u4e86\uff0c\u670d\u52a1\u5668\uff08\u53ef\u4ee5\u901a\u8fc7\u914d\u7f6e\u9879\uff09\u68c0\u6d4bCookie\u662f\u88ab\u8bbe\u6210\u4e86small\u5462\uff0c medium\u5462\u8fd8\u662flarge\u51b3\u5b9a\u56fe\u7247\u7684src\u5730\u5740\u5230\u5e95\u662f\u54ea\u4e2a\u3002<\/p>\n<p>github\u4e0a\u9879\u76ee\u6709\u4e2ademo, \u70b9\u51fb<a href=\"http:\/\/filamentgroup.com\/examples\/responsive-images-new\/demos\/A-Default\/demo.html\">\u8fd9\u91cc<\/a>\u8bbf\u95ee\u3002<\/p>\n<p>\u9996\u6b21\u8fdb\u5165\u7684\u65f6\u5019\u662f\u4e2a\u5c0f\u56fe\uff08Cookie\u9996\u6b21\u5199\u5165\uff0c\u540e\u53f0\u65e0\u6cd5\u83b7\u53d6\uff09\uff0c\u518d\u6b21\u5237\u65b0\u5c31\u662f\u4e2a\u5927\u5bb6\u4f19\u4e86\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" alt=\"\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201202\/2012-02-15_192900.jpg\" title=\"\u9996\u6b21\u8f7d\u5165\u7684\u5c0f\u56fe \" width=\"440\" height=\"308\" \/> <img loading=\"lazy\" decoding=\"async\" alt=\"\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201202\/2012-02-15_193514.jpg\" title=\"\u518d\u6b21\u5237\u65b0\u7684\u5927\u56fe\" width=\"414\" height=\"287\" \/><\/p>\n<p><strong>\u4e0e\u54cd\u5e94\u5e03\u5c40\u5dee\u5f02<\/strong><br \/>\n\u867d\u8bf4\u8be5\u6280\u672f\u6709\u54cd\u5e94\u5e03\u5c40\u7684\u5f71\u5b50\uff0c\u4f46\u662f\uff0c\u5b9e\u9645\u4e0a\u5b9e\u73b0\u7684\u539f\u7406\u4ee5\u53ca\u6548\u679c\u7b49\u662f\u5927\u76f8\u5f84\u5ead\u7684\u3002\u5dee\u5f02\u5728\u4e8e\uff1a<\/p>\n<ol>\n<li>\u975eCSS\u6280\u672f\uff0c\u4e3aCookie + server\u5b9e\u73b0<\/li>\n<li>\u4e0e\u6d4f\u89c8\u5668\u5bbd\u5ea6\u65e0\u5173\uff0c\u5373\u6539\u53d8\u6d4f\u89c8\u5668\u5bbd\u5ea6\u56fe\u7247\u4e0d\u4f1a\u6709\u53d8\u5316<\/li>\n<li>\u517c\u5bb9\u5177\u6709\u8003\u53e4\u4ef7\u503c\u7684\u6d4f\u89c8\u5668<\/li>\n<\/ol>\n<p>\u8fd9\u79cd\u54cd\u5e94\u65b9\u5f0f\u8ddf\u4eac\u4e1c\u5546\u57ce\u9996\u9875\u51e0\u4e4e\u5982\u51fa\u4e00\u8f99\u3002\u9875\u9762\u5bbd\u5ea6\u7531\u7528\u6237\u663e\u793a\u5668\u5206\u8fa8\u7387\u51b3\u5b9a\uff08\u975e\u6d4f\u89c8\u5668\uff09\u3002<\/p>\n<p>\u4e0b\u56fe\u4e3a1024\u50cf\u7d20\u663e\u793a\u5668\u5bbd\u5ea6\u548c1680\u50cf\u7d20\u4e0b(1280\u50cf\u7d20\u5bbd\u5ea6\u5c31\u8db3\u591f\u4e86)\u7684\u4eac\u4e1c\u5546\u57ce\u9875\u9762\u5e03\u5c40\u622a\u56fe\u3002<br \/>\n<img loading=\"lazy\" decoding=\"async\" width=\"514\" height=\"282\" class=\"alignnone\" title=\"\u4eac\u4e1c\u5546\u57ce1024\u5bbd\u5ea6\u4e0b\u9996\u9875\u5e03\u5c40 \u5f20\u946b\u65ed-\u946b\u7a7a\u95f4-\u946b\u751f\u6d3b\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201109\/2011-09-19_173215.png\" alt=\"\u4eac\u4e1c\u5546\u57ce1024\u5bbd\u5ea6\u4e0b\u9996\u9875\u5e03\u5c40 \u5f20\u946b\u65ed-\u946b\u7a7a\u95f4-\u946b\u751f\u6d3b\"> <img loading=\"lazy\" decoding=\"async\" width=\"514\" height=\"281\" class=\"alignnone\" title=\"\u4eac\u4e1c\u5546\u57ce1680\u50cf\u7d20\u5bbd\u5ea6\u4e0b\u9996\u9875\u5e03\u5c40 \u5f20\u946b\u65ed-\u946b\u7a7a\u95f4-\u946b\u751f\u6d3b\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201109\/2011-09-19_173342.png\" alt=\"\u4eac\u4e1c\u5546\u57ce1680\u50cf\u7d20\u5bbd\u5ea6\u4e0b\u9996\u9875\u5e03\u5c40 \u5f20\u946b\u65ed-\u946b\u7a7a\u95f4-\u946b\u751f\u6d3b\"><\/p>\n<p><strong>\u517c\u5bb9\u6027<\/strong><br \/>\n\u56e0\u4e3a\u4f7f\u7528Cookie\uff0c\u5e76\u975eCSS3 <code>media queries<\/code>\uff0c\u56e0\u6b64\u4f4e\u7248\u672cIE\u6d4f\u89c8\u5668\u4e0b\u4e5f\u662fOK\u7684\u3002<\/p>\n<p><strong>\u5982\u679c\u8bbe\u5907\u4e0d\u652f\u6301Javascript\u4ee5\u53caCookie<\/strong><br \/>\n\u5982\u679c\u8bbf\u95ee\u8bbe\u5907\u4e0d\u652f\u6301Javascript\u4ee5\u53caCookie, \u5219\u56fe\u7247\u4f1a\u663e\u793amobile\u624b\u673a\u4e0a\u5c3a\u5bf8\uff0c\u5373\u5c0f\u5c3a\u5bf8\u3002<\/p>\n<p><strong>\u53ef\u9009\u9879<\/strong><br \/>\n<a href=\"http:\/\/filamentgroup.com\/examples\/responsive-images-new\/responsive-images.js\">responsive-images.js<\/a>\u662f\u4e00\u4e2a\u975e\u5e38\u5c0f\u7684\u811a\u672c\uff0c\u4e0d\u4f1a\u5176\u4e5f\u4f1a\u6709\u53ef\u9009\u9879\u7684\u3002\u53ef\u9009\u53c2\u6570\u4e3a\u4e00\u4e2a\u5168\u5c40\u7684\u5bf9\u8c61\u5b57\u9762\u91cf\u3002<\/p>\n<div class=\"zxx_code\">\n<pre><code>&lt;script&gt;\n    <span style=\"color:green;\">\/\/\u8fd9\u91cc\u4e3a\u914d\u7f6e\u9879:<\/span>\n    var responsive_images = {\n        \"key\": \"value\"\n    };\n&lt;\/script&gt;\n<\/code><\/pre>\n<\/div>\n<p>\u5bf9\u8c61\u5b57\u9762\u91cf\u7684\u540d\u79f0\u662f\u56fa\u5b9a\u7684\uff0c\u4e3aresponsive_images\uff0c\u652f\u6301\u7684\u5173\u952e\u5b57\u3001\u9ed8\u8ba4\u503c\u548c\u542b\u4e49\u89c1\u4e0b\u8868\uff1a<\/p>\n<table width=\"100%\" border=\"0\" cellspacing=\"1\" cellpadding=\"0\" class=\"params_table\">\n<tr>\n<th scope=\"col\">\u5173\u952e\u5b57<\/th>\n<th scope=\"col\">\u9ed8\u8ba4\u503c<\/th>\n<th scope=\"col\">\u91ca\u4e49<\/th>\n<\/tr>\n<tr>\n<td>cookieName<\/td>\n<td>rwd-screensize<\/td>\n<td>Cookie\u540d<\/td>\n<\/tr>\n<tr>\n<td>cookieValue<\/td>\n<td>sw &gt; 500 ?  ( sw &gt; 1000 ? &quot;large&quot; : &quot;medium&quot; ) : &quot;small&quot;<\/td>\n<td>Cookie\u503c<\/td>\n<\/tr>\n<tr>\n<td>cookieAge<\/td>\n<td>30000<\/td>\n<td>\u8fc7\u671f\u65f6\u95f4\uff0c\u5355\u4f4d\u6beb\u79d2<\/td>\n<\/tr>\n<tr>\n<td>cookieDomain<\/td>\n<td>\u5f53\u524d\u8bbf\u95ee<\/td>\n<td>Cookie\u57df<\/td>\n<\/tr>\n<tr>\n<td>cookiePath<\/td>\n<td>\/<\/td>\n<td>Cookie\u8def\u5f84<\/td>\n<\/tr>\n<\/table>\n<h3>\u4e09\u3001\u5176\u4ed6\u540c\u884c\u7684Cookie\u5b9e\u73b0<\/h3>\n<p>keithclark\u5728\u53bb\u5e74\u590f\u5929\u7684\u65f6\u5019\u5c31\u8bf4\u8fc7\u54cd\u5e94\u56fe\u7247\uff0c\u4e0d\u8fc7\u5176\u6587\u7ae0\u66f4\u591a\u7684\u662f\u5c55\u793a\u670d\u52a1\u5668\u7aef\u7684\u5904\u7406(PHP)\uff0c\u539f\u7406\u4e0e\u4e0a\u9762\u7c7b\u4f3c\u3002<\/p>\n<p>\u5148\u662f\u5199Cookie, \u5f88\u7b80\u77ed\u7684\uff1a<\/p>\n<div class=\"zxx_code\">\n<pre>document.cookie = \"device_dimensions=\" + screen.width + \"x\" + screen.height; <\/pre>\n<\/div>\n<p>\u7136\u540e\u5c31\u662fPHP\u8bed\u8a00\u7684\u7efd\u653e\u4e86\uff1a<\/p>\n<style>.comment{color:green;}<\/style>\n<div class=\"zxx_code\">\n<pre>\n&lt;?php\n  $device_width = 0;\n  $device_height = 0;\n  $file = $_SERVER[<span class=\"string\">'QUERY_STRING'<\/span>];\n\n  <span class=\"keyword\">if<\/span> (file_exists($file)) {\n\n    <span class=\"comment\">\/\/ Read the device viewport dimensions<\/span>\n    <span class=\"keyword\">if<\/span> (isset($_COOKIE[<span class=\"string\">'device_dimensions'<\/span>])) {\n      $dimensions = explode(<span class=\"string\">'x'<\/span>, $_COOKIE[<span class=\"string\">'device_dimensions'<\/span>]);\n      <span class=\"keyword\">if<\/span> (count($dimensions)==2) {\n        $device_width = intval($dimensions[0]);\n        $device_height = intval($dimensions[1]);\n      }\n    }\n\n    <span class=\"keyword\">if<\/span> ($device_width &gt; 0) {\n\n      $fileext = pathinfo($file, PATHINFO_EXTENSION);\n\n      <span class=\"comment\">\/\/ Low resolution image<\/span>\n      <span class=\"keyword\">if<\/span> ($device_width &lt;= 800) {\n        $output_file = substr_replace($file, <span class=\"string\">'-low'<\/span>, -strlen($fileext)-1, 0);\n      } \n\n      <span class=\"comment\">\/\/ Medium resolution image<\/span>\n      <span class=\"keyword\">else<\/span> <span class=\"keyword\">if<\/span> ($device_width &lt;= 1024) {\n        $output_file = substr_replace($file, <span class=\"string\">'-med'<\/span>, -strlen($fileext)-1, 0);\n      }\n\n      <span class=\"comment\">\/\/ check the file exists<\/span>\n      <span class=\"keyword\">if<\/span> (isset($output_file) &amp;&amp; file_exists($output_file)) {\n        $file = $output_file;\n      }\n    }\n\n    <span class=\"comment\">\/\/ return the file;<\/span>\n    readfile($file);\n  }\n\n?&gt;<\/pre>\n<\/div>\n<p>\u7136\u540eHTML\u7aef\u7684\u5e90\u5c71\u9762\u76ee\uff1a<\/p>\n<div class=\"zxx_code\">\n<pre><span class=\"dtd\">&lt;!doctype html&gt;<\/span>\n<span class=\"tag\">&lt;html&gt;<\/span>\n<span class=\"tag\">&lt;head&gt;<\/span>\n  <span class=\"tag\">&lt;title&gt;<\/span>Responsive Images Test<span class=\"tag\">&lt;\/title&gt;<\/span>\n  <span class=\"tag\">&lt;meta <span class=\"attname\">charset=<\/span><span class=\"attvalue\">\"utf-8\"<\/span>&gt;<\/span>\n  <span class=\"tag\">&lt;script&gt;<\/span>\n    document.cookie = \"device_dimensions=\" + screen.width + \"x\" + screen.height;\n  <span class=\"tag\">&lt;\/script&gt;<\/span>\n<span class=\"tag\">&lt;\/head&gt;<\/span>\n<span class=\"tag\">&lt;body&gt;<\/span>\n  <span class=\"tag\">&lt;img <span class=\"attname\">src=<\/span><span class=\"attvalue\">\"images\/?test.png\"<\/span>&gt;<\/span>\n  <span class=\"comment\">&lt;!-- \u4e0a\u9762\u7b49\u540c\u4e8e\uff1a &lt;img src=\"images\/index.php?test.png\"&gt; --&gt;<\/span>\n<span class=\"tag\">&lt;\/body&gt;<\/span>\n<span class=\"tag\">&lt;\/html&gt;<\/span>\n<\/pre>\n<\/div>\n<p>\u8fd9\u4e2a\u561b\u5e0c\u671b\u5bf9\u559c\u6b22copy\u4ee3\u7801\u7684\u540c\u884c\u6709\u6240\u5e2e\u52a9\u3002<\/p>\n<h3>\u56db\u3001\u4f7f\u7528noscript\u6807\u7b7e\u521b\u5efa\u54cd\u5e94\u56fe\u7247<\/h3>\n<p>\u4e0a\u9762\u4f8b\u5b50\u4e2d\u7684\u54cd\u5e94\u56fe\u7247\u5728\u4e24\u79cd\u60c5\u51b5\u4e0b\u4f1a\u76f4\u63a5mobile\u5c3a\u5bf8\u56fe\u7247\u663e\u793a\uff1a\u4e00\u662f\u7ad9\u70b9\u9996\u6b21\u8f7d\u5165\u7684\u65f6\u5019\uff1b\u4e8c\u662fCookie\u7981\u7528\u6216\u662fJavascript\u51fa\u53bb\u649e\u52b3\u65af\u83b1\u65af\u7684\u65f6\u5019\u3002<\/p>\n<p>\u8fd9\u91cc\u7684<code>noscript<\/code>\u6807\u7b7e\u521b\u5efa\u6cd5\u5219\u57fa\u672c\u6ca1\u6709\u8fd9\u4e9b\u95ee\u9898\uff0c\u56e0\u4e3a\u8be5\u65b9\u6cd5\u5b8c\u5168\u501f\u52a9\u5ba2\u6237\u7aef\u5b9e\u73b0\u3002<\/p>\n<p>\u540c\u6837\uff0cgithub\u4e0a\u6709\u8be5\u65b9\u6cd5\u7684\u9879\u76ee\u9875\u9762 &#8211; <a class=\"a_link\" target=\"_blank\" href=\"https:\/\/github.com\/futurechimp\/responsive_image_tag\">futurechimp \/ responsive_image_tag<\/a>.<\/p>\n<p>\u8fd9\u91cc\u7684\u54cd\u5e94\u56fe\u7247\u6280\u672f\u8c8c\u4f3c\u4e0d\u9700\u8981Cookie\u7684\u524d\u540e\u7aef\u901a\u8baf\uff0c\u800c\u662f\u501f\u52a9<code>noscript<\/code>\u6807\u7b7e\u4ee5\u53caJS\u5b9e\u73b0\u3002<\/p>\n<p>\u4e0b\u9762\u5c31\u662f\u5b9e\u73b0\u7684<strong>\u6b65\u6b65\u5c55\u793a<\/strong>\uff1a<\/p>\n<style>.ta{color:blue;}.an{color:#f09;}pre .s{color:#c30; font-family:verdana;}.c{color:green;}<\/style>\n<p>\u9996\u5148\u662fHTML\u90e8\u5206\uff1a<\/p>\n<div class=\"zxx_code\">\n<pre><span class=\"ta\">&lt;span<\/span> <span class=\"an\">class<\/span>=<span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">img-placeholder<\/span><span class=\"dl\">\"<\/span><\/span><span class=\"ta\">&gt;<\/span><span class=\"ta\">&lt;\/span&gt;<\/span><tt>\n<\/tt><span class=\"ta\">&lt;noscript<\/span> <span class=\"an\">data-mobilesrc<\/span>=<span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">small.jpg<\/span><span class=\"dl\">\"<\/span><\/span> <span class=\"an\">data-fullsrc<\/span>=<span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">big.jpg<\/span><span class=\"dl\">\"<\/span><\/span> <span class=\"an\">data-alttext<\/span>=<span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">your alt text<\/span><span class=\"dl\">\"<\/span><\/span> <span class=\"an\">class<\/span>=<span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">responsivize<\/span><span class=\"dl\">\"<\/span><\/span><span class=\"ta\">&gt;<\/span><tt>\n<\/tt>   <span class=\"ta\">&lt;img<\/span> <span class=\"an\">src<\/span>=<span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">big.jpg<\/span><span class=\"dl\">\"<\/span><\/span><span class=\"ta\">&gt;<\/span><tt>\n<\/tt><span class=\"ta\">&lt;\/noscript&gt;<\/span><\/pre>\n<\/div>\n<p>\u4e0a\u9762\u4ee3\u7801\u4e2d\uff0c\u7c7b\u540d\u4e3a<code>img-placeholder<\/code>\u7684<code>span<\/code>\u6807\u7b7e\u662f\u7528\u6765\u5360\u4f4d\u5b50\u548c\u63d2\u5165\u56fe\u7247\u7684\u3002<code>&lt;noscript><\/code>\u4e2d\u7684\u56fe\u7247\u9ed8\u8ba4\u8c03\u7528\u7684\u662f\u5927\u56fe\u5730\u5740\uff0c\u5728JavaScript\u88ab\u7981\u7528\u7684\u65f6\u5019\u4f1a\u663e\u793a\u3002<\/p>\n<p>\u4e0b\u9762\u8981\u505a\u7684\u5c31\u662f\u4f7f\u7528JavaScript\u5224\u522b\u5f53\u524d\u663e\u793a\u8bbe\u5907\u662fmobile\u7c7b\u522b\u8fd8\u662fdesktop\u7c7b\u522b\uff1a<\/p>\n<div class=\"zxx_code\">\n<pre><span class=\"kw\">var<\/span> responsiveImageTag = {<tt>\n<\/tt>    <span class=\"fu\">replaceInitialImages<\/span>:<span class=\"kw\">function<\/span>() {<tt>\n<\/tt>        <span class=\"kw\">var<\/span> platform = <span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">desktop<\/span><span class=\"dl\">\"<\/span><\/span>;<tt>\n<\/tt>        <span class=\"kw\">var<\/span> responsiveImages = <span class=\"pd\">$$<\/span>(<span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">.responsivize<\/span><span class=\"dl\">\"<\/span><\/span>);<tt>\n<\/tt>        <span class=\"kw\">var<\/span> i,<tt>\n<\/tt>            noOfresponsiveImages = responsiveImages.length;<tt>\n<\/tt>        <span class=\"c\">\/\/\u5f53\u524d\u663e\u793a\u5668\u8bbe\u5907\u5bbd\u5ea6\u6d4b\u8bd5<\/span><tt>\n<\/tt>        <span class=\"kw\">if<\/span>(screen.width &lt;= <span class=\"i\">767<\/span>){ \n                <span class=\"c\">\/\/767px, \u6bd4 ipad \u5c0f\u7684\u90fd\u8ba4\u4e3a\u662f mobile<\/span><tt>\n<\/tt>          platform = <span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">mobile<\/span><span class=\"dl\">\"<\/span><\/span>;<tt>\n<\/tt>        }<tt>\n<\/tt>        <tt>\n<\/tt>       <span class=\"c\">\/\/set initial source element on image<\/span><tt>\n<\/tt>       <span class=\"kw\">for<\/span>(i = <span class=\"i\">0<\/span>; i &lt; noOfresponsiveImages; i = i + <span class=\"i\">1<\/span> ){<tt>\n<\/tt>       <span class=\"kw\">var<\/span> noScriptElem = <span class=\"pd\">$<\/span>(responsiveImages[i]);<tt>\n<\/tt><tt>\n<\/tt><\/pre>\n<\/div>\n<p>\u65e2\u7136\u77e5\u9053\u4e86\u8bbe\u5907\u7c7b\u522b\uff0c\u6211\u4eec\u5c31\u53ef\u4ee5\u6839\u636e\u8fd9\u4e2a\u7c7b\u522b\u5206\u522b\u8f7d\u5165\u5bf9\u5e94\u5c3a\u5bf8\u7684\u56fe\u7247\u4e86\u3002\u5bf9\u5e94\u8bbe\u5907\u5c3a\u5bf8\u56fe\u7247\u5730\u5740\u4ee5\u901a\u8fc7HTML5\u81ea\u5b9a\u4e49\u5c5e\u6027<code>data-<\/code>\u5b9a\u4e49\u5728\u4e86<code>&lt;noscript><\/code>\u4e0a\uff0c\u56e0\u6b64\uff0c\u6211\u4eec\u5c31\u6709\u4ee3\u7801\uff08\u7d27\u63a5\u4e0a\u9762\uff09\uff1a<\/p>\n<div class=\"zxx_code\">\n<pre><span class=\"kw\">    var<\/span> img = window.document.createElement(<span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">img<\/span><span class=\"dl\">\"<\/span><\/span>);<tt>\n<\/tt>       img.alt = noScriptElem.attr(<span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">data-alttext<\/span><span class=\"dl\">\"<\/span><\/span>);<tt>\n<\/tt>       <span class=\"kw\">if<\/span>(platform === <span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">mobile<\/span><span class=\"dl\">\"<\/span><\/span>){<tt>\n<\/tt>          img.src = noScriptElem.attr(<span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">data-mobilesrc<\/span><span class=\"dl\">\"<\/span><\/span>);<tt>\n<\/tt>       }<span class=\"kw\">else<\/span>{<tt>\n<\/tt>          img.src = noScriptElem.attr(<span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">data-fullsrc<\/span><span class=\"dl\">\"<\/span><\/span>);<tt>\n<\/tt>       }<tt>\n<\/tt>       img.className = <span class=\"s\"><span class=\"dl\">\"<\/span><span class=\"k\">responsive<\/span><span class=\"dl\">\"<\/span><\/span>;<tt>\n<\/tt><\/pre>\n<\/div>\n<p>\u7136\u540e\uff0c\u628a\u56fe\u7247\u4ee5DOM\u7684\u5f62\u5f0f\u63d2\u5165\u5230\u4e0a\u9762\u7528\u6765\u5360\u4f4d\u7684<code>span<\/code>\u6807\u7b7e\u5143\u7d20\u5185\uff0c\u4e8e\u662f\u5c31\u5927\u529f\u544a\u6210\uff01<\/p>\n<div class=\"zxx_code\">\n<pre>       noScriptElem.prev().append(img);   <tt>\n<\/tt>       noScriptElem.hide();<tt>\n<\/tt>     }<tt>\n<\/tt>   }<tt>\n<\/tt>};<\/pre>\n<\/div>\n<h3>\u4e94\u3001\u53e6\u7c7b\u56fe\u7247\u54cd\u5e94<\/h3>\n<p>Jeremy Keith\u63d0\u51fa\u4e86\u53e6\u5916\u4e00\u79cd\u54cd\u5e94\u56fe\u7247\u6280\u672f\uff0c\u53ef\u4ee5\u7b97\u662f\u4e00\u79cd\u56fe\u7247\u52a0\u8f7d\u4f18\u5316\u6280\u672f\u3002<\/p>\n<p>\u5982\u4e0b\uff1a<br \/>\n\u65e0\u8bba\u662f\u5c0f\u5c4f\u5e55\u7684\u624b\u673a\uff0c\u8fd8\u662f\u5927\u5c4f\u5e55\u7684\u684c\u9762\u8bbe\u5907\uff0c\u9ed8\u8ba4<code>img<\/code>\u94fe\u63a5\u7684\u56fe\u7247\u90fd\u662f\u5c0f\u56fe\uff08\u5982\u4e0b\uff09\u3002<br \/>\n<img loading=\"lazy\" decoding=\"async\" alt=\"\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201202\/response_image_m.jpg\" title=\"\u793a\u4f8b\u539f\u59cb\u5c0f\u56fe\" class=\"alignnone\" width=\"240\" height=\"179\" \/><\/p>\n<p>\u7136\u540e\u9875\u9762\u8f7d\u5165\u5b8c\u6bd5\u540e\uff0c\u5982\u679c\u663e\u793a\u5668\u5bbd\u5ea6\u8d85\u8fc7\u4e00\u4e2a\u9650\u5236\uff0c\u5219<code>src<\/code>\u5730\u5740\u5207\u6362\u6210\u5927\u56fe\u5730\u5740\u3002<\/p>\n<p>\u5176\u4e2d\uff0c\u6709\u4e2a\u6bd4\u8f83\u5173\u952e\u7684\u5c31\u662f\uff0c\u5982\u679c\u663e\u793a\u5668\u5bbd\u5ea6\u5927\u4e8e\u67d0\u4e2a\u503c\uff0c\u5c0f\u56fe\u7684\u9ad8\u5bbd\u5c3a\u5bf8\u662f\u8981\u88ab\u653e\u5927\u7684\uff0c\u4e5f\u5c31\u662f\u8bf4\u5c0f\u56fe\u4f1a\u88ab\u62c9\u4f38\u663e\u793a\u3002\u8fd9\u79cd\u5c3a\u5bf8\u7684\u63a7\u5236\u501f\u52a9\u4e8eCSS3\uff1a<\/p>\n<div class=\"zxx_code\">\n<pre>@media screen and (min-width: 50em) {\n    .photo {\n        width: 500px;\n        height: 375px;\n    }\n}<\/pre>\n<\/div>\n<p>\u4e8e\u662f\u4e4e\uff0c\u6211\u4eec\u4f1a\u770b\u5230\uff0c\u9875\u9762\u8f7d\u5165\u540e\u7684\u6a21\u7cca\u56fe\u7247\uff1a<br \/>\n<img decoding=\"async\" alt=\"\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201202\/response_image_m.jpg\" title=\"\u56fe\u7247\u62c9\u4f38\" class=\"alignnone\" width=\"500\" \/><\/p>\n<p>\u4f46\u662f\uff0c\u8fd9\u79cd\u6a21\u7cca\u6548\u679c\u662f\u6682\u65f6\u7684\uff0c\u56e0\u4e3a\u9875\u9762loaded\u5b8c\u6bd5\u540e\uff0c\u6211\u4eec\u4f1a\u6839\u636e\u5bbd\u5ea6\u8303\u56f4\u518d\u6b21\u4fee\u6539<code>img<\/code>\u7684<code>src<\/code>\u5730\u5740\uff0c\u800c\u8f7d\u5165\u6e05\u6670\u56fe\u7247\u3002<br \/>\n<img loading=\"lazy\" decoding=\"async\" alt=\"\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201202\/response_image_l.jpg\" title=\"\u5927\u5c3a\u5bf8\u56fe\u7247\" class=\"alignnone\" width=\"500\" height=\"374\" \/><\/p>\n<p>\u6211\u8bb0\u5f97\u4ee5\u524d\u767e\u5ea6\u56fe\u7247\u6d4f\u89c8\u5c31\u662f\u8fd9\u79cd\u6548\u679c\u6ef4\u3002<\/p>\n<p>\u8fd9\u79cd\u56fe\u7247\u54cd\u5e94\u5b9e\u73b0\u7684\u597d\u5904\u5728\u4e8e\u63d0\u9ad8\u4e86\u9875\u9762\u7684\u6027\u80fd\uff0c\u867d\u7136\u770b\u4e0a\u53bb\u597d\u50cf\u6bd4\u503c\u52a0\u8f7d\u5927\u5c3a\u5bf8\u56fe\u7247\u591a\u4e86\u5dee\u4e0d\u591a20K\u3002<\/p>\n<p>\u6839\u636e\u4f5c\u8005\u7684\u793a\u4f8b\uff0c\u5927\u56fe\u7684\u5730\u5740\u4f7f\u7528HTML5 <code>data-<\/code>\u81ea\u5b9a\u4e49\u5c5e\u6027\u85cf\u533f\uff1a<\/p>\n<div class=\"zxx_code\">\n<pre>&lt;img src=\"seed.jpg\" alt=\"\u523a\u523a\u7684\u79cd\u5b50\" <span style=\"color:#cd0000;\">data-fullsrc<\/span>=\"seed-large.jpg\"> <\/pre>\n<\/div>\n<h3>\u516d\u3001\u53c2\u8003\u6587\u7ae0<\/h3>\n<ul>\n<li><a href=\"https:\/\/github.com\/filamentgroup\/Responsive-Images\/tree\/cookie-driven\">Responsive Design Images<\/a><\/li>\n<li><a href=\"http:\/\/drupal.org\/project\/responsive_images\">Responsive Images<\/a><\/li>\n<li><a href=\"http:\/\/blog.keithclark.co.uk\/responsive-images-using-cookies\/\">Responsive images using cookies<\/a><\/li>\n<li>Mairead: <a href=\"http:\/\/www.headlondon.com\/our-thoughts\/technology\/posts\/creating-responsive-images-using-the-noscript-tag\">Creating responsive images using the noscript tag<\/a> <\/li>\n<li><a href=\"http:\/\/www.alistapart.com\/articles\/responsive-images-how-they-almost-worked-and-what-we-need\/\">Responsive Images: How they Almost Worked and What We Need<\/a><\/li>\n<li><a href=\"http:\/\/adactio.com\/journal\/5208\/\">Image-y nation <\/a><\/li>\n<\/ul>\n<p>\u672c\u6587\u4e3a\u539f\u521b\u6587\u7ae0\uff0c\u8f6c\u8f7d\u8bf7\u6ce8\u660e\u6765\u81ea<a href=\"http:\/\/www.zhangxinxu.com\/\">\u5f20\u946b\u65ed-\u946b\u7a7a\u95f4-\u946b\u751f\u6d3b<\/a>[<a href=\"http:\/\/www.zhangxinxu.com\/\">http:\/\/www.zhangxinxu.com<\/a>]<br \/>\n\u672c\u6587\u5730\u5740\uff1a<a href=\"http:\/\/www.zhangxinxu.com\/wordpress\/?p=2204\">http:\/\/www.zhangxinxu.com\/wordpress\/?p=2204<\/a><\/p>\n<p>\uff08\u672c\u7bc7\u5b8c\uff09<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u54cd\u5e94\u56fe\u7247\u6280\u672f\u53ef\u4ee5\u8bf4\u662f\u54cd\u5e94\u5e03\u5c40\u884d\u751f\u51fa\u6765\u7684\u4e00\u4e2a\u5c0f\u5206\u652f\u3002\u8bf4\u767d\u4e86\uff0c\u5c31\u662f\u4e0d\u540c\u663e\u793a\u5668\u5bbd\u5ea6\u4e0b\u8c03\u7528\u4e0d\u540c\u7684\u56fe\u7247\u3002<br \/>\n\u8fd9\u73a9\u610f\uff0c\u6700\u8fd1\u5728\u56fd\u5916\u8ba8\u8bba\u5f88\u706b\uff0c\u6709\u51e0\u79cd\u4e0d\u540c\u7684\u5b9e\u73b0\u65b9\u6cd5\uff0c\u4f46\u90fd\u5e76\u4e0d\u590d\u6742\u3002\u672c\u6587\u5c31\u5c06\u7b80\u5355\u4ecb\u7ecd\u8fd9\u4e9b\u65b9\u6cd5\uff0c\u4ece\u539f\u7406\u5230\u5b9e\u8df5\u3002\u540c\u6837\u7684\uff0c\u4ee3\u7801\u793a\u4f8b\uff0c\u622a\u56fe\uff0cdemo\u9875\u9762\uff0c\u90fd\u6709\u3002\u5e0c\u671b\u672c\u6587\u7684\u5185\u5bb9\u80fd\u591f\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":[7],"tags":[255,13,498,681,151,443,680,640,117,194],"_links":{"self":[{"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/posts\/2204"}],"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=2204"}],"version-history":[{"count":0,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/posts\/2204\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/media?parent=2204"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/categories?post=2204"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/tags?post=2204"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}