javascript read file workaround (to view script but not load it)

EDIT My question was misleading in that it sounded like I wanted to read/write to the client machine when what I meant was that i want to read a script, not load it, from the source computer. I just assumed since you can summon (load) a script like so

<script LANGUAGE="javascript" SRC="source.js"></script>

Then there must be some way to read source.js before, during or after loading it. I ask because I am still 开发者_JS百科trying to find an answer to my previous question here. I am trying to find some way to make an object/function/class aware of the code that gave rise to it, with comments and tabs and all.

you could load it via ajax and access it as a string

$.ajax({
    type: "GET",
    dataType: "text",
    url: "jsLoader.php",
    success: function(data){
        alert("Length: " + data.length.toString());
        eval(data);
    }
});

Or:

$.ajax({
    type: "GET",
    dataType: "text",
    url: "source.js",
    success: function(data){
        alert("Length: " + data.length.toString());
        $("head").append('<script type="text/javascript">' + data + '</script>');
    }
});

your question is kind of confusing, but it sounds like you want a way of accessing an object's code. To be honest I don't know how far you can get with this approach, and it won't include comments, but you can always just use toString().

e.g.

function myFunc() {
    var somestuff = "my function's code";
};

function myClass() {
    var that = this;
    this.classFunc = function() {
        var somethingelse = "my class function's code";
    }
}

alert(myFunc.toString() + '\n\n' + myClass.toString());

Maybe I'm a little confused by your question, but first things first:

<script LANGUAGE="javascript" SRC="source.js"></script>

Does NOT read from client's machine, it reads from the web context that the page was loaded from. If the html page you're loading is www.google.com for example, then src="source.js" will load www.google.com/source.js

If I understand your question correctly though, I think the answer to your questions is that source.js does NOT get read asynchronously in the loading of the web page. Let's say source.js contains only this line.

var variable = {};

In index.html, you have this:

<script type="text/javascript">
  alert(typeof(variable));
</script>

<script type="text/javascript" src="source.js"></script>

<script type="text/javascript">
  alert(typeof(variable));
</script>

Then, the first alert is going to give you "undefined", and the second alert will give you "object". So, if you want to test if source.js is loaded or not, you can simply do a quick conditional:

if (typeof(variable) != "undefined") { doSomething(); }

One way to get around this would be to setup a php script which fetches the code serverside, wraps it in a function/object, and while doing so assigns the code as a string variable, somewhat like so

/*Get js script at $filename*/
$script = fread($handle, filesize($fileName));

/*Add the code as a string*/
$codeAsString = file_get_contents($fileName);
$script .= '_code=' . json_encode($codeAsString) . ';';

But this doesn't solve the bigger problem of not being able to debug the code. The reason for this is that I am using eval rather than including the scripts. The former executes the code, whereas the latter updates the DOM then executes the code. Only the latter will provide useful debugging info (see here).