title: jquery array group by
body: <p>I have array like this</p>
  
  <pre><code>abcArr = [["A", 10], ["B", 20], ["A",30],["C",40]]
  </code></pre>
  
  <p>how can I group and sum values by A, B, C... </p>
  
  <pre><code>$.each(abcArr , function() {
      if (this[0] == this[0]) { 
        this[1] + this[1] 
      }; // I know this will simple double [1] values :(
  });
  </code></pre>
  
  <p>desired result should be</p>
  
  <pre><code>[["A", 40], ["B", 20], ["C",30]]
  </code></pre>