title: merge arrays and convert to JSON string
body: <p>I have two arrays consist of strings
  <code>["25","36","32"]</code> and <code>["GradeA", "GradeB", "GradeC"]</code></p>
  
  <p>I want to merge them all together and want to produce JSON string something like this: </p>
  
  <p><code>{"GradeA" : "25", "GradeB" : "36", "GradeC": "32"}</code></p>
  
  <p>How do I do this in js? </p>