Can't insert js programmatically if it uses document.write

问题

I am trying to insert js files programmatically, using jquery and something like this:

var script = document.createElement( 'script' );
script.type = 'text/javascript';
script.src = 'http://someurl/test.js';
$('body').append(script);

It works fine, if test.js contains an alert or some simple code it works fine, but if the file test.js contains document.write, and the file including the js is hosted on another domain than test.js (or localhost), nothing happens and firebug shows the error :

A call to document.write() from an asynchronously-loaded external script was ignored.

If the test.js and the file that include it are hosted on the same domain, on chrome it still wont work but on firefox the document.write gets executed fine but the page stays "loading" forever and sniffer show request to all the files with "pending" status.

What other methods to include js files programmatically could I try?

回答1:

use innerHTML instead of using document,write.

and use following code to register script,

(function() {
    var jq = document.createElement('script');
    jq.type = 'text/javascript';
    jq.async = true;
    jq.src = 'http://someurl/test.js';
    var s = document.body.getElementsByTagName('script')[0];
    s.parentNode.insertBefore(jq, s);
})();

回答2:

Document.write is ONLY for synchronous tasks when the html is loaded (for the very first time), never for asynchronous tasks like the one you are trying to do.

回答3:

What you want to do is dynamically insert a <script> DOM element into the HEAD element. I had this script sitting around. As an example, it's a race condition, but you get the idea. Call load_js with the URL. This is done for many modern APIs, and it's your best friend for cross-domain JavaScript.

<html>
    <head>
        <script>
            var load_js = function(data, callback)
            {
                    var head = document.getElementsByTagName("head")[0];

                    var script = document.createElement("script");
                    script.type = "text/javascript";
                    script.src = data;
                    head.appendChild(script);

                    if(callback != undefined)
                            callback();
            }

            load_js("http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js");

            setTimeout(function() {
                $('body').html('loaded');
            }, 1000);
        </script>
    </head>

    <body></body>
</html>

回答4:

There isn't anything wrong with your approach to inserting JavaScript. document.write just sucks a little bit. It is only for synchronous tasks, so putting a document.write in a separate script file is asking for trouble. People do it anyway. The solution I've seen most often for this is to override document.write.

来源：https://stackoverflow.com/questions/8753182/cant-insert-js-programmatically-if-it-uses-document-write

标签

javascript

jquery

include

javascript-injection