一、程式碼示例：

<html>

<head>

<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />

<title>動態載入JS檔案</title>

</head>

<body>

<button id="btn" onclick="loanScript('test.js'),callback">載入js檔案</button>

<script type="text/javascript">

    function callback(){

        console.log("script load complete");

        loadSuccess();

    }

    function loanScript(url,callbackFun){

        var script = document.createElement("script");

        script.type = "text/javascript";

        //相容IE瀏覽器

        if(script.readyState){

            script.onreadystatechange = function(){

                if(script.readyState == "loaded" || script.readyState == "complete"){

                    script.onreadystatechange = null;

                    callbackFun();

                }

            }

        }else{//其他瀏覽器

            script.onload = function(){

                callbackFun();

            };

        }

        script.src = url;

        document.getElementsByTagName("head")[0].appendChild(script);

    }

</script>

</body>

</html>

注意除了Firefox和Opera保證指令碼檔案按照程式碼順序載入，其他瀏覽器不保證檔案按照你指定的順序載入，可通過串聯操作保證檔案的載入次序程式碼如下

window.onload=function(){

    loadScript("file1.js",function(){

        loadScript("file2.js",function(){

            loadScript("file3.js",function(){

                alert("all js document are loaded");

            });

        });

    });

}