title: What is the Typescript equivalent to C# LINQ GroupBy ?
body: <p>I am using Angular with Typescript. I have array of objects with multiple properties. I have grouped them in server side code and set duplicate property. When user updates the list I have to loop though the list and find duplicates in the client side. Is there any C# LINQ GroupBy equivalent in Typescript?</p>
  
  <p>Here is my C# LINQ code:</p>
  
  <pre><code>listMP.Where(item =&gt; item.Type == "Other").GroupBy(i =&gt; new { i.Type, i.Name, i.Address1, i.City }).Where(g =&gt; g.Count() &gt; 1)
  .SelectMany(g=&gt;g.Select(gg =&gt;gg.Id));
  </code></pre>