title: How to concatenate two strings without duplicates in JavaScript
body: <p>I have two strings as below:</p>
  
  <pre><code>var str1 = "5YRS,AC,ALAR";
  var str2 = "MON,5YRS,TRAU";
  </code></pre>
  
  <p>I want to merge these two strings into one string and to remove duplicates in this.
  I tried the below method:</p>
  
  <pre><code>var main_str = str1.concat(str2) //result: "5YRS,AC,ALARMON,5YRS,TRAU"
  </code></pre>
  
  <p>Result which i got is getting merged at on end and if i push any string dynamically it is not showing the desired result. Is there any new ES6 implementation to get a method which checks both null check and return unique string values.</p>