What is the meaning of ^= operator in JS

Question

I am trying to figure out this operator on JS -

'string' ^= 'string';

But I can not find ant information. Is that a comparison or assignment ?

Thanks.

If the title was't so generic I'd might find this duplicate :( — shannoga, Apr 07 '13 at 13:17

score 7 · Accepted Answer · edited Apr 07 '13 at 13:23

7

myVar ^= 5 is the same as myVar = myVar ^ 5. ^ is the bitwise xor operator

Let's say myVar was set to 2

5 in binary is: 101
2 in binary is: 010

Exclusive "or" checks the first bit of both numbers and sees 1,0 and returns 1 then sees 0,1 and returns 1 and sees 1,0 and returns 1.

Thus 111 which converted back to decimal is 7

So 5^2 is 7

var myVar = 2;
myVar ^= 5;
alert(myVar); // 7

edited Apr 07 '13 at 13:23

David G

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answered Apr 07 '13 at 13:20

Thalaivar

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You might consider editing the `5^2 is 7` part. I thought for a moment you meant '5 to the power of 2', which is, of course, 25 and not 7. – 11684 Apr 07 '13 at 13:21
@11684: Math.pow does that in JavaScript. Nothing to be confused about here. alert(5^2);//7 – Thalaivar Apr 07 '13 at 13:24
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I know, but it still was confusing. I +1'ed after you wrapped it in `s though. – 11684 Apr 07 '13 at 13:30

score 4 · Answer 2 · answered Apr 07 '13 at 13:16

4

^ (caret) is the Bitwise XOR (Exclusive Or) operator. As with more common operator combinations like +=, a ^= b is equivalent to a = a^b.

See the Javascript documentation from Mozilla for more details.

answered Apr 07 '13 at 13:16

ASGM

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d'alar'cop · Answer 3 · 2013-04-07T13:16:42.450

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x ^= y is bitwise XOR and shorthand for x = x^y - and so is technically an "assignment" to answer your question. And to be precise the single operator '^' indicates the bitwise XOR.

edited Apr 07 '13 at 13:16

answered Apr 07 '13 at 13:12

d'alar'cop

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No, XOR is `!=`. `^` is bitwise xor. – Bergi Apr 07 '13 at 13:15
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Huh? That is 'is not'. @Bergi – 11684 Apr 07 '13 at 13:16
@11684: Then check the truth tables. This answer is useless as long it doesn't mention that it's a [bitwise operator](https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Operators/Bitwise_Operators) (in an assignment shorthand) – Bergi Apr 07 '13 at 13:17
@Bergi Yes, you're right. Too quick. – d'alar'cop Apr 07 '13 at 13:19
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@bergi Hey, now I realize you were right. `!=` indeed _is_ XOR. – 11684 Apr 07 '13 at 13:23

score 1 · Answer 4 · answered Apr 07 '13 at 13:20

As d'alar'cop (and several others by now) already pointed out, this means something called XOR. I always hate to read a wikipedia explanation, so I'm going to put another explanation here:

'XOR' means 'eXclusive OR'. What is that? First an example:

11000110 -- random byte
10010100
--------- ^ -- XOR
01010010

XOR is some bitwise operation, returning two if one of two bits is 1 and the other 0. If they're both 1, it's 'and', not 'exclusive or' ('normal or' would allow two 1's).

What is the meaning of ^= operator in JS

4 Answers4