本文共 1992 字，大约阅读时间需要 6 分钟。
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一般现代浏览器通过侦听事件获得脚本加载完成时的状态
var script = document.createElement( ' script ' ); script.type = ' text/javascript ' ; // Firefox, Chrome script.onload = function (){ alert( ' script loaded! ' ); }; script.src = ' http://code.jquery.com/jquery-1.4.2.min.js ' ; document.getElementsByTagName( ' head ' )[ 0 ].appendChild(script);
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ie支持另外一种方式，会触发readystatechange事件
loading:开始下载
complete:所有数据已准备就绪
var script = document.createElement( ' script ' ); script.type = ' text/javascript ' ; // IE script.onreadystatechange = function (){ if (script.readyState == ' loaded ' || script.readyState == ' complete ' ){ script.onreadystatechange = null ; alert( ' Script loaded ' ); } } script.src = ' http://code.jquery.com/jquery-1.4.2.min.js ' ; document.getElementsByTagName( ' head ' )[ 0 ].appendChild(script);
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兼容方法
/* * * 载入脚本 * @param {String} url 载入的地址 * @param {Function} callback 载入后需执行的函数 */ function loadScript(url, callback){ var script = document.createElement( ' script ' ); script.type = ' text/javascript ' ; // IE if (script.readyState){ script.onreadystatechange = function (){ if (script.readyState == ' loaded ' || script.readyState == ' complete ' ){ script.onreadystatechange = null ; callback(); } } } else { // 非IE script.onload = function (){ callback(); } } script.src = null ; document.getElementsByTagName( ' head ' )[ 0 ].appendChild(script); } // example loadScript( ' http://code.jquery.com/jquery-1.4.2.min.js ' , function (){ alert( ' File is loaded! ' ); })
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XMLRequest脚本注入
var xhr = new XMLHttpRequest();xhr.open( ' get ' , ' http://code.jquery.com/jquery-1.4.2.min.js ' , true );xhr.onreadystatechange = function (){ if (xhr.readySate == 4 ){ if (xhr.status >= 200 && shr.status < 300 || xhr.status == 304 ){ // 200 有效响应; 304 从缓存读取 var script = document.createElement( ' script ' ); script.type = ' text/javascript ' ; script.text = xhr.responseText; document.body.appendChild(script); } }};xhr.send( null );
转载于:https://www.cnblogs.com/milk/archive/2012/04/13/2445802.html