title: JavaScript Add key to each value in array
body: <p>I have this array below that consists of a simple array. What i'm trying to accomplish is to put a key <code>id</code> in front of every array value to achieve something like this <code>["id:a", "id:b","id:c","id:d"]</code> is there a easy way to accomplish this? any help would be greatly appreciated thank you.</p>
  
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  <pre class="snippet-code-js lang-js prettyprint-override"><code>var test = ['a','b','c','d']</code></pre>
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