title: How can I create a Map with non-unique keys in JavaScript/TypeScript?
body: <p>To interface with existing code, I am hoping to implement a Map with non-unique keys in JavaScript/TypeScript (for a web app in Angular).</p>
  
  <p>I know that Maps in JavaScript/TypeScript enforce unique keys.  How can I implement a "non-unique" Map?</p>
  
  <p>Creating an array of Key-Value objects does not work as the structure does not de-serialize from JSON in the correct shape for the existing consumer code.</p>
  
  <p>For example, I am hoping to create something like the following structure:</p>
  
  <pre><code>vehicleOptions : NonUniqueMap&lt;key: string, value: {color: string, isTowingCapable: boolean}&gt;
  {
    "Truck", { "Red", true },
    "Compact Sedan", { "Black", false },
    "Compact Sedan", { "Blue", false }
  }
  </code></pre>