Solve the following summation of series using JavaScript?

 <script>
  var n=6;
  for(i=1;i<=n;i++){   
      var total=0;
      for(j=1;j<=i;j++){
        document.write(j)
        if(j<i){            
         if(i!=1){  
            document.write("+")    
         }
        }
        total+=j;
      }

    document.write("="+total+"<br>");
  }
</script>