title: indexOf() method returns -1 when item is present in list
body: <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>let mobile = [
    "‭+9384849202",
    "‭+5808789645",
    "‭+0989645643",
    "‭+7864769845",
  ]
  
  console.log(mobile.indexOf("+7864769845"))</code></pre>
  </div>
  </div>
  </p>
  <p>the result of this is <code>-1</code> when the expected result is <code>3</code></p>
  <p>thought it was a type error at first, but now I'm not sure?</p>