Decrement operator

Question

I was having trouble with a piece of code and found out that the problem was that decrement (--) was not doing anything. Instead I am using -1, but what is it that it doesn't funciton?

_01 is simply a number

 minOne = document.getElementById("ctdwnTimeDispSec").value=_01--;

This is what works now

 minOne = document.getElementById("ctdwnTimeDispSec").value=_01-1;

Answer 1

You should use --_01

_01-- will do -1 after the expression.

Answer 2

The -- operator will decrement the number it's operated on, during or after the statement, based on whether it is placed before or after the number.

e.g. Placing -- after a, will modify the value of a, on the following line.

var a=5
var b=a--

afterwards, will equal:

a=4
b=5

e.g. Placing -- before a, will modify a on the same line.

var a=5
var b=--a

afterwards, will equal:

a=4
b=4

When you use var b=a-1, the javascript will execute the a-1 on that line, making b=4, and not changing a. Make sense?

Answer 3

You will need to use the pre decrrement operator instead of post decrement operator, other you can get the decremented value after that expression.