title: concatenation in array javascript using plus sign
body: <p>I was trying to concatenate two array using + sign but result i was getting is:first array's last element is concatenated to first element of second array why it is happening is there is any specific reason  I tried</p>
  
  <pre><code>var a=[1,2,3]; 
  var b=[5,7,8]; 
  console.log(a+b);
  </code></pre>
  
  <p>I got result 1,2,35,7,8</p>