title: Check if key exists in map
body: <p>I read that to check if a key exists in a <strong><em>Map</em></strong> , we can use the <strong><em>has</em></strong> method
  I am using the following example:</p>
  
  <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>var mp = new Map();
  mp["abc-def"] = 123;
  if (mp.has("abc-def")) {
    console.log("found");
  } else {
    console.log("not found");
  }</code></pre>
  </div>
  </div>
  </p>
  
  <p>Any suggestion on why the <strong><em>has</em></strong> method is not working here?</p>