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I have some crazy app done almost 100% by manipulating the DOM and I find myself in the unfortunate position of changing something in it. As there are probably around 100 different scripts that do God knows what, I have no clue in which file should I look to make my changes. So, I want to ask, is there a way (using Firebug maybe or something similar) to know where a specific piece of html was generated? I'm a C developer, so I'm not very good at this, it drives me crazy.
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Are all the elements added at the page load, or partially in the response to the user input? (clicking etc.)
console.log or create a breakpoint, to inspect the current page state. You can try playing with breakpoints to see the available variables properties inside those function to adjust what you push to console.log.For this code:
<!doctype html>
<html>
<head>
<script type="text/javascript">
// this should work in Firefox but it does not -- https://bugzilla.mozilla.org/show_bug.cgi?id=618379
// works at least in Opera, probably Chrome too
Node.prototype._appendChild = Node.prototype.appendChild;
Node.prototype.appendChild = function(child) {
console.log("appending " + child + " to " + this);
return this._appendChild(child); // call the original function with the original parameters
}
// this works in Firefox
document._createElement = document.createElement;
document.createElement = function(tagName){
console.log("creating " + tagName);
return this._createElement(tagName);
}
</script>
</head>
<body>
<script type="text/javascript">
var p = document.createElement("p");
p.appendChild( document.createTextNode("abc"));
document.body.appendChild(p);
</script>
</body>
</html>
Opera outputs:
creating p appendChild.html:14
appending [object Text] to [object HTMLParagraphElement] appendChild.html:7
appending [object HTMLParagraphElement] to [object HTMLBodyElement] appendChild.html:7
To overcome the weakness of Firefox (that you can't override appendChild), you may use the trick: place the code below instead in the top of your HTML
<script>
Node.prototype._appendChild = function(child) {
console.log("appending " + child + " to " + this);
return this.appendChild(child)
};
</script>
and then, use Fiddler proxy by creating auto-responders (WMV tutorial, 9.9 MB) where you manually replace all calls to .appendChild with ._appendChild (you can use Notepad++ for "find replace in all opened files"). Creating auto-responders and hand-tampering requests can be mundane, but it's extremely powerful. To quickly create auto-responder rule, load the page when Fiddler is active, then drag'n'drop files as in the picture below. For each file, right click and choose "Generate File" from menu (this will put a file on the desktop) or create a file by yourself in different location. (it's good to open Fiddler-generated files and remove response headers from them; BTW "Generate file" puts real contents only if the response header was 200, so make sure to load the page with CTRL-F5 to skip the cache).
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