title: Javascript remove row from multidimensional array when elements are duplicated
body: <p>I have the following array.</p>
  
  <pre><code>[{
    'firstname': 'John',
    'surname': 'Smith',
    'HouseNo': 'firtree farm'
  }, {
    'firstname': 'Paul',
    'surname': 'Smith',
    'HouseNo': 'firtree farm'
  }, {
    'firstname': 'John',
    'surname': 'Smith',
    'HouseNo': 'firtreefarm'
  }, {
    'firstname': 'John',
    'surname': 'Smith',
    'HouseNo': 'firtree farmhouse'
  }, {
    'firstname': 'Paul',
    'surname': 'Smith',
    'HouseNo': 'firtree farmhouse'
  }, {
    'firstname': 'Paul',
    'surname': 'Smith',
    'HouseNo': 'FirTree farmhouse'
  }]
  </code></pre>
  
  <p>I need to produce another array that contains no duplicates of element 'HouseNo' and just the element 'HouseNo. Also it need to be case insensitive.</p>
  
  <p>ie.</p>
  
  <pre><code>[{
    'HouseNo': 'firtree farm'
  }, {
    'HouseNo': 'firtreefarm'
  }, {
    'HouseNo': 'firtree farmhouse'
  }, {
    'HouseNo': 'FirTree farmhouse'
  }]
  </code></pre>
  
  <p>The application is a returned set of address's based on a postcode search. I can then offer a filtered list of unique houseNo's they can choose form.</p>
  
  <p>MrWarby</p>