Can’t append element

Question

The Good News is:

It’s 100% working.

Just add something inside the script tag such as alert('voila!');. The right question you might want to ask perhaps, “Why didn’t I see it in the DOM?”.

Karl Swedberg has made a nice explanation to visitor’s comment in jQuery API site. I ~~don’t~~ want to repeat all his words, you can read directly ~~there~~ here (I found it hard to navigate through the comments there).

All of jQuery’s insertion methods use
a domManip function internally to
clean/process elements before and
after they are inserted into the DOM.
One of the things the domManip
function does is pull out any script
elements about to be inserted and run
them through an “evalScript routine”
rather than inject them with the rest
of the DOM fragment. It inserts the
scripts separately, evaluates them,
and then removes them from the DOM.

I believe that one of the reasons jQuery
does this is to avoid “Permission
Denied” errors that can occur in
Internet Explorer when inserting
scripts under certain circumstances.
It also avoids repeatedly
inserting/evaluating the same script
(which could potentially cause
problems) if it is within a containing
element that you are inserting and
then moving around the DOM.

The next thing is, I’ll summarize what’s the bad news by using .append() function to add a script.

And The Bad News is..

You can’t debug your code.

I’m not joking, even if you add debugger; keyword between the line you want to set as breakpoint, you’ll be end up getting only the call stack of the object without seeing the breakpoint on the source code, (not to mention that this keyword only works in webkit browser, all other major browsers seems to omit this keyword).

If you fully understand what your code does, than this will be a minor drawback. But if you don’t, you will end up adding a debugger; keyword all over the place just to find out what’s wrong with your (or my) code. Anyway, there’s an alternative, don’t forget that javascript can natively manipulate HTML DOM.

Workaround.

Use javascript (not jQuery) to manipulate HTML DOM

If you don’t want to lose debugging capability, than you can use javascript native HTML DOM manipulation. Consider this example:

var script   = document.createElement("script");
script.type  = "text/javascript";
script.src   = "https://stackoverflow.com/questions/610995/path/to/your/javascript.js";    // use this for linked script
script.text  = "alert('voila!');"               // use this for inline script
document.body.appendChild(script);

There it is, just like the old days isn’t it. And don’t forget to clean things up whether in the DOM or in the memory for all object that’s referenced and not needed anymore to prevent memory leaks. You can consider this code to clean things up:

document.body.removechild(document.body.lastChild);
delete UnusedReferencedObjects; // replace UnusedReferencedObject with any object you created in the script you load.

The drawback from this workaround is that you may accidentally add a duplicate script, and that’s bad. From here you can slightly mimic .append() function by adding an object verification before adding, and removing the script from the DOM right after it was added. Consider this example:

function AddScript(url, object){
    if (object != null){
        // add script
        var script   = document.createElement("script");
        script.type  = "text/javascript";
        script.src   = "https://stackoverflow.com/questions/610995/path/to/your/javascript.js";
        document.body.appendChild(script);

        // remove from the dom
        document.body.removeChild(document.body.lastChild);
        return true;
    } else {
        return false;
    };
};

function DeleteObject(UnusedReferencedObjects) {
    delete UnusedReferencedObjects;
}

This way, you can add script with debugging capability while safe from script duplicity. This is just a prototype, you can expand for whatever you want it to be. I have been using this approach and quite satisfied with this. Sure enough I will never use jQuery .append() to add a script.

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