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jQuery Analyze Plugin

This plugin is intended to help out with jQuery development by providing runtime feedback on how selectors, events and the DOM is utilized. In its current state it's not so much of a help as it is a proof of concept. The code to enable analysis and generate a report has been written but it is useless without a set of sensible analyzers.

The plugin is equipped to give feedback on use of jQuery selectors, bound events and DOM structure. Additionally it will measure the performance of jQuery selectors and event handlers.

Demo

You can view a demo here of jqanalyze analyzing the jQuery UI demo page.

How not to use

Please don't take any of the current feedback very seriously. It is only intended as a proof of concept. Also, I didn't do a lot of testing in IE so you're on your own there.

How to use

To use the plugin in your jQuery project, simply add the plugin directory to your root and add the following script tag to your HTML. For the best results, add it right after the jQuery script tag.

<script type="text/javascript"
src="path/to/jqanalyze/jquery.analyze.js"></script>

If you then open the page in your browser you'll see a yellow and black striped bar on the right. Hover over that bar to see the report for that page. The report is updated in real time so if you continue to interact with the page you'll get more (interesting) results. It doesn't matter if you close the report or leave it open in the meantime.

How to contribute

As mentioned, right now the most lacking part are the actual analyzers. There's three different types of analyzers you can add or modify. The simplest is the DOM analyzer.

Adding a DOM analyzer

This creates a warning for having an H2 element but no H1 element:

$.analyze.addDOMAnalyzer(function() {
    if ($('h2').length && !$('h1').length) {
        return 'h1 should be the top header';
    }
});

Adding a selector analyzer

There's two ways to add a selector analyzer. The simplest is a regular-expression based check:

$.analyze.addSelectorRegexp(
        /(:[\w]+)/,
        'jQuery pseudo classes like <code>$1</code> can be slow.');

The addSelectorRegexp takes two arguments:

  • The regular expression that should be matched.
  • The warning message displayed when it matches.

This one will check for pseudo classes like :first and :input. Note the $1 in the warning message. It will be replaced by the matching group in the regular expression.

The other way to add a selector analyzer is more flexible.

$.analyze.addSelectorAnalyzer(function(selector, result, duration) {
    /*
     - selector: The selector string used
     - result:   The jQuery object returned
     - duration: The time in ms it took to execute the selector query
    Do whatever you want here and return a string if a warning should be
    displayed.
    */
});

Adding an event binding analyzer

Adding an event binding analyzer is very similar to the second method of adding a selector analyzer:

$.analyze.addEventAnalyzer(function(type, result, duration) {
    /*
     - type:     The type of event (click, load, etc)
     - result:   The jQuery object returned
     - duration: The time in ms it took to execute the selector query
    Do whatever you want here and return a string if a warning should be
    displayed
    */
});

Credits

I'd like to thank Gijs Kruitbosch and Karl Swedberg for their ideas and help during the development.