title: Group by on JSON array using Underscore JS
body: <p>I have a JSON array object as follows:</p>
  
  <pre><code>var orders = [{
      orderId: 1,
      firstName: 'John',
      lastName: 'Smith',
      address: {
          street: '123 Main Street',
          city: 'New York',
          zip: 10001
      }
  }, {
      orderId: 2,
      firstName: 'John',
      lastName: 'Smith',
      address: {
          street: '456 Main Street',
          city: 'New York',
          zip: 10001
      }
  }, {
      orderId: 3,
      firstName: 'John',
      lastName: 'Smith',
      address: {
          street: '123 Main Street',
          city: 'New York',
          zip: 10001
      }
  }, {
      orderId: 4,
      firstName: 'John',
      lastName: 'Smith',
      address: {
          street: '123 Main Street',
          city: 'New York',
          zip: 10002
      }
  }];
  </code></pre>
  
  <p>I am trying to use <code>underscore.js</code> to create a new array object, grouped by the address to meet the use case of displaying all orders that have been shipped to <code>123 Main Street, New York, 1001</code>.</p>
  
  <p>Is <code>underscore.js</code> the right approach to do this? If so, how should I do so? Any hints will be helpful. </p>