title: Create new unique JSON form Existing JSON by filter
body: <p>I want to create new unique JSON form Existing JSON by filter.</p>
  
  <p>I want to following json:</p>
  
  <pre><code>var newJson = [
    {"38:1":["40:89","39:86","40:88"]},
    {"38:6":["39:339"]}
  ]
  </code></pre>
  
  <p>I have following existing json.</p>
  
  <pre><code>var existJson = [ 
    {d: "40:89", t: "38:1"},
    {d: "39:86", t: "38:1"},
    {d: "40:88", t: "38:1"},
    {d: "39:339", t: "38:6"}
  ]
  </code></pre>
  
  <p>I want to create fitter and created new unique JSON like <code>newJson</code> 
  need to some filter which get unique <code>t</code> as key and <code>d</code> as array value.</p>
  
  <pre><code>{ t : [d1, d2, d3] }
  </code></pre>