Limited Lives - Building JavaScript Games for Phones, Tablets, and Desktop - page 130

Figure 10-2. The Painter game showing the player the remaining number of lives
A Shorter Notation for Incrementing Counters
Many while instructions, especially those that use a counter, have a body that contains an
instruction for incrementing a variable. This can be done with the following instruction:
i = i + 1;
As a side note, especially because of these kinds of instructions, it's unwise to express the
assignment as “is”. The value of i can of course never be the same as i + 1 , but the value of i
becomes the old value of i , plus 1. These kinds of instructions are very common in programs, so a
special, shorter notation exists that does exactly the same thing:
i++;
The ++ can be expressed as “is incremented.” Because this operator is placed after the variable it
operates on, the ++ operator is called a postfix operator . To increment a variable by more than 1,
there is another notation
i += 2;
which means the same as
i = i + 2;