jQuery Audit


jQuery Audit

Install it from the Chrome Web Store.

jQuery Audit is a Chrome Developer Tools extension for debugging auditing jQuery — it creates a sidebar in the Elements panel containing jQuery delegated events, internal data, and more, as live DOM nodes, functions, and objects.

jQuery Audit panel

Live DOM nodes, functions, and objects
  • Variables in the jQuery Audit sidebar behave like objects in the Sources panelScope Variables sidebar. You can right-click on a function and goto "Show Function Definition", or hover over a DOM node to highlight it in the document, as well as right-clicking it to "Reveal in Elements Panel".

show function definition

Direct access to the document and window objects
  • The document and the window objects don't have representations in the Elements panel but can nonetheless be event targets and/or have associated jQuery data. jQuery Audit adds two comment nodes above the <!DOCTYPE> to represent them. The <!--@(document)--> as a stand-in for the document object, and the <!--@(window)--> as a stand-in for the window object. Select either to audit the represented object in the jQuery Audit sidebar.

document & window

Requirements: jQuery Audit does a typeof window.jQuery === 'function' whenever a node is selected. If it can't find a jQuery function in the global scope, the sidebar will display Error: "@(window.jQuery is missing)".

Tip: Text wrapped in @(...) are "messages" from jQuery Audit. This was the compromise made to get live objects in the sidebar and be able to show informative messages.

Sidebar sections

@(this element)
  • The element currently selected.
  • Data contains the would-be result of invoking $(element).data(). jQuery Audit doesn't invoke .data() because calling it creates a data object in jQuery's internal store if one doesn't already exist for that element. Instead, jQuery Audit directly looks in the internal store for the data object and returns it. If there isn't one, you'll see @(none), or if it's an empty object you'll see @(empty Object).
  • These are the events that the element would react to. That means any delegated events, or any directly bound events that don't delegate. (Directly bound events are under Internal Dataevents). For each event name, there is a corresponding jQuery event object associated with it, that has:
    • a delegator: The ancestor element that delegates the event, or @(this element) when the event is directly bound to the element and there is no delegation.
    • a handler: The function that handles the event. More often than not, the handler is a bound function and not directly the function that does the "work". The section below on Finding bound handlers shows you where common binder functions store the bound function.
    • And more.
Internal Data
  • The internal data jQuery keeps on the element - it is the result of calling $._data(element). This is not the same as the data object from $(element).data(), though the data object is kept here in the internal store.
  • The value of HTMLElement.dataset. This is not the same as Data above, but closely related to it. HTMLElement.dataset contains the raw data-* attributes. While Data is the parsed content of any data-* attributes jQuery found on the element along with any other arbitrary information. (jQuery converts Boolean, Number and JSON in data-* attributes when you call .data()).
own HTML
  • The result of removing the innerHTML from the outerHTML of an element. This helps debug character encoding issues, since what the Elements panel shows is a decoded "pretty" version of the HTML and not the actual HTML.

Finding bound handlers

Often event handlers are bound functions. In these cases, the function under Eventsevent_namehandler is the binder function and not the bindee. Depending on the binder used, the bindee function is usually near by.

_.bind from Lo-Dash
  • Expand the handler function followed by the __bindData__ property. In this array, the first element is the bindee function, the other elements contain the this context and any parameters to be partially applied. Older versions of Lo-Dash might not have this structure.

    Lo-Dash bind

_.bind from Underscore and native Function.prototype.bind
  • Underscore uses to the native bind function. A clear sign that the binder is the native bind function is function () { [native code] } for a handler. Expand the handler to locate the bindee function is under [[TargetFunction]]. The this context is found in [[BoundThis]] and any parameters to be partially applied are in [[BoundArgs]].

    Native bind

$.proxy from jQuery
  • With $.proxy the bindee can't be found as a property on the binder but rather in a Closure. Expand the handler, followed by <function scope> and then the inner-most Closure. One of the variables in this scope contains the bindee - the name of the variable that contains the bindee will likely vary because of minification.

    jQuery proxy


  • Does jQuery Audit work with <iframe>'s?

Yes, if the <iframe> has a jQuery function (regardless of the parent having jQuery or not) and it's not restricted by the same-origin policy.

  • How do I remove <!--@(document)--> and <!--@(window)-->?

Run jQueryAudit() in the console. When you close the developer tools the two comment nodes are removed and the jQueryAudit object is removed.

  • Why exactly the @(...)?

The content of a SidebarPane can be an HTML page, a JSON object, or "the result of an expression". An HTML page, nor a JSON object, have the ability to display "live" objects. The reason for making this extension was so that I could find a delegated event and be able to use "Show Function Definition" on the handler. For that effect, the contents of the sidebar is actually "the result of an expression" with a lot of trickery to make it look not-so-ugly. So, to differentiate between actual object data and informational messages I went with @(...) so it wouldn't be easily confused with string data.

  • Why the name Audit?

I am a lawyer. Yes, really. Went to law school, passed the bar, and I'm a fully admitted member of the New York State Bar Association. So, yeah, that's why Audit came to mind when I was thinking of a name.

Disclaimer: I am not related to the jQuery project.