Use this instead:

var divID = question- + (i+1)

It's a fairly common problem and doesn't just happen in JavaScript. The idea is that + can represent both concatenation and addition.

Since the + operator will be handled left-to-right the decisions in your code look like this:

• question- + i: since question- is a string, we'll do concatenation, resulting in question-1


• question-1 + 1: since queston-1 is a string, we'll do concatenation, resulting in question-11.

With question- + (i+1) it's different:

• since the (i+1) is in parenthesis, its value must be calculated before the first + can be applied:
  
  
  
  
  • i is numeric, 1 is numeric, so we'll do addition, resulting in 2
  
  


• question- + 2: since question- is a string, we'll do concatenation, resulting in question-2.