What exactly does % do in JavaScript?

Question

I'm trying to convert some JavaScript code into Java, but I do not know what the % character between two numeric variables does:

    testvalue = somevalue%anothervalue;

What does this mean or what would the same statement be in Java?

I also have this in JavaScript:

    if(somevalue%2 == 1){
    }

What does %2 mean here?

@jlordo, it seems he is translating from one to another. I do not think there is any confusion. — jn1kk, Feb 06 '13 at 14:46
Have you searched for JavaScript math operators? I recently needed to know if JS had this operator an that search gave me very straightforward results. I won't answer, however, because I think there's a good fish vs fishing opportunity here. — Carl, Feb 06 '13 at 14:49

score 5 · Accepted Answer · edited Feb 13 '18 at 18:41

5

It's the modulus operator.

This returns "the first operand modulo the second operand", which is the remainder when you substract (or add) as much of the second operand off/to of the first, to get as close as possible to 0.

Here's an example:

 5  % 2 ==  1  ( 5  = 2*2   +1)
 6  % 2 ==  0  ( 6  = 2*3   +0)
 12 % 5 ==  2  ( 12 = 5*2   +2)
-5  % 2 == -1  (-5  = 2*-2  -1)
-6  % 2 ==  0  (-6  = 2*-3  -0)
-12 % 5 == -2  (-12 = 5*-2  -2)
//                           ^ That's the result of the modulo.

edited Feb 13 '18 at 18:41

T.Galisnky

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answered Feb 06 '13 at 14:48

Cerbrus

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your description does not make sense for negative numbers. – Alex Feb 06 '13 at 14:48
@Alex: And "Division remainder" does? `5 / 2 == 2.5`. The other answers aren't any less vague than mine was. Any way, edited. – Cerbrus Feb 06 '13 at 14:56

Josh Mein · Answer 2 · 2017-05-23T12:34:45.000

3

It is the modulus operator. The modulus operator performs division on the two values and gives you the remainder as the output.

For example:

var testValue = 5 % 3;

testValue output would be 2

edited May 23 '17 at 12:34

answered Feb 06 '13 at 14:46

Josh Mein

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The link is broken. – Peter Mortensen May 22 '17 at 21:18
@PeterMortensen I have updated the link, and with your rep, you could have easily done it as well. – Josh Mein May 23 '17 at 12:36

score 0 · Answer 3 · edited May 22 '17 at 21:15

0

It is the modulo operator. It gives you the remainder of somevalue/anothervalue, i.e. 10%4 === 2.

edited May 22 '17 at 21:15

Peter Mortensen

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answered Feb 06 '13 at 14:46

Alexander Gessler

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score 0 · Answer 4 · edited May 22 '17 at 21:18

0

It's the modulo operator in both Java and JavaScript and other programming languages.

It returns the remainder of a division, e.g.,

5 % 2 = 1

edited May 22 '17 at 21:18

Peter Mortensen

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answered Feb 06 '13 at 14:46

stacker

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score 0 · Answer 5 · answered Feb 06 '13 at 14:46

0

It's "modulus" or remainder division - in other words, returning the remainder of the division.

See this page on JavaScript Operators.

answered Feb 06 '13 at 14:46

Mike

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score 0 · Answer 6 · edited Feb 06 '13 at 14:50

0

It performs a modulo calcuation. That is: determining the divison reminder. And yes, Java uses the same syntax for this.

Example: 5%3 = 2

Because 3 goes into 5 once, and there is a reminder of 2.

edited Feb 06 '13 at 14:50

Josh Mein

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answered Feb 06 '13 at 14:47

Marc Fischer

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score 0 · Answer 7 · answered Feb 06 '13 at 15:07

X%5

means the remaining of x/5 so if x=12 then x%5 = 2 if you want to increase a number in a loop up to a maximum

<button onclick="incX();">increase up to 5</button>
<script type="text/javascript">
    var x=0;
    function incX(){
        x%=5;
        x++;
        alert("X = "+x);
    }
</script>

What exactly does % do in JavaScript?

7 Answers7