Increment

The Increment operator (++) increments its operand by one.

• If used as a postfix, then it returns the value before incrementing.
• If used as a prefix, then it returns the value after incrementing.

// postfix
var a = 5;     // 5 
var b = a++;   // 5 
var c = a      // 6

In this case, a is incremented after setting b. So, b will be 5, and c will be 6.

// prefix 
var a = 5;    // 5 
var b = ++a;  // 6 
var c = a;    // 6

In this case, a is incremented before setting b. So, b will be 6, and c will be 6.

The increment and decrement operators are commonly used in for loops, for example:

for (var i = 0; i < 42; ++i)
{
  // do something awesome!
}

Notice how the prefix variant is used. This ensures that a temporarily variable isn’t needlessly created (to return the value prior to the operation).