javascript - Load external Javascript on function call

Question

I would like to know how to load an external Javascript into my document from a function.

Answer 1

This is one way:

function loadDaFun() {
   var script = document.createElement('script');
   script.src = '/path/to/your/script.js';
   var head = document.getElementsByTagName("head")[0];
   head.appendChild(script);
}

Answer 2

@seth的答案是完全正确的，但是您不需要将插入的script元素留在 DOM 上，您可以在加载后立即将其删除，并且您可能想知道插入的脚本何时可以使用，例如，您可以：

function loadScript(url, completeCallback) {
   var script = document.createElement('script'), done = false,
       head = document.getElementsByTagName("head")[0];
   script.src = url;
   script.onload = script.onreadystatechange = function(){
     if ( !done && (!this.readyState ||
          this.readyState == "loaded" || this.readyState == "complete") ) {
       done = true;
       completeCallback();

      // IE memory leak
      script.onload = script.onreadystatechange = null;
      head.removeChild( script );
    }
  };
  head.appendChild(script);
}

用法：

loadScript("http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js",
            function () { alert('jQuery has been loaded.'); });

Answer 3

使用 AJAX 获取它，然后 eval() 代码。