jQuery how to find an element based on a data-attribute value?

Question

I\'ve got the following scenario:

var el = \'li\';

and there are 5

\'s on the page each with a data-slide=numb

Answer 1

I improved upon psycho brm's filterByData extension to jQuery.

Where the former extension searched on a key-value pair, with this extension you can additionally search for the presence of a data attribute, irrespective of its value.

(function ($) {

    $.fn.filterByData = function (prop, val) {
        var $self = this;
        if (typeof val === 'undefined') {
            return $self.filter(
                function () { return typeof $(this).data(prop) !== 'undefined'; }
            );
        }
        return $self.filter(
            function () { return $(this).data(prop) == val; }
        );
    };

})(window.jQuery);

Usage:

$('').data('x', 1).filterByData('x', 1).length    // output: 1
$('').data('x', 1).filterByData('x').length       // output: 1

// test data
function extractData() {
  log('data-prop=val ...... ' + $('div').filterByData('prop', 'val').length);
  log('data-prop .......... ' + $('div').filterByData('prop').length);
  log('data-random ........ ' + $('div').filterByData('random').length);
  log('data-test .......... ' + $('div').filterByData('test').length);
  log('data-test=anyval ... ' + $('div').filterByData('test', 'anyval').length);
}

$(document).ready(function() {
  $('#b5').data('test', 'anyval');
});

// the actual extension
(function($) {

  $.fn.filterByData = function(prop, val) {
    var $self = this;
    if (typeof val === 'undefined') {
      return $self.filter(

        function() {
          return typeof $(this).data(prop) !== 'undefined';
        });
    }
    return $self.filter(

      function() {
        return $(this).data(prop) == val;
      });
  };

})(window.jQuery);


//just to quickly log
function log(txt) {
  if (window.console && console.log) {
    console.log(txt);
    //} else {
    //  alert('You need a console to check the results');
  }
  $("#result").append(txt + "
");
}

#bPratik {
  font-family: monospace;
}

  
Setup
  
Data added inline :: data-prop="val"
  
Data added inline :: data-prop="val"
  
Data added inline :: data-prop="diffval"
  
Data added inline :: data-test="val"
  
Data will be added via jQuery
  
Output
  


  

  Reveal

Or the fiddle: http://jsfiddle.net/PTqmE/46/