title: Check if a string exists in an array case insensitively
body: <p>Declaration:</p>
  
  <pre><code>let listArray = ["kashif"]
  let word = "kashif"
  </code></pre>
  
  <p>then this </p>
  
  <pre><code>contains(listArray, word) 
  </code></pre>
  
  <p>Returns true but if declaration is:</p>
  
  <pre><code>let word = "Kashif"
  </code></pre>
  
  <p>then it returns false because comparison is case sensitive. </p>
  
  <p>How to make this comparison case insensitive?  </p>