直接document.write
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   | <script language="javascript">     document.write("<script src='test.js'><\/script>"); </script> 
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动态改变已有script的src属性
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   | <script src='' id="s1"></script> <script language="javascript">     var scriptE=document.getElementById("s1");     scriptE.src="test.js" </script>
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动态创建script元素
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   | <script>     var headDom = document.getElementsByTagName('HEAD').item(0);     var scriptDom= document.createElement("script");     scriptDom.type = "text/javascript";     scriptDom.src="test.js";     headDom.appendChild(scriptDom); </script> 
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使用jQuery
使用getScript(url,callback)方法实现动态加载js文件
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   | $.getScript('test.js',function(){     alert('done'); });
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参考资料
https://www.jb51.net/article/17992.htm
https://www.jb51.net/article/139481.htm