Meaning of >>, <<, | and & in JavaScript

Question

I was working with a base64 encoding script, but it is throwing a lot of warnings in JSLint.

Can someone tell me what's the meaning of these symbols in JavaScript?

>>,<<,|,&

Here's an example of code with those symbols:

if ((c > 127) && (c < 2048)) {
    utftext += String.fromCharCode((c >> 6) | 192);
    utftext += String.fromCharCode((c & 63) | 128);
}

I would like to rewrite this so that it gets validated by JSLint.

Good references help https://developer.mozilla.org/en/JavaScript/Reference/Operators — epascarello, Dec 27 '10 at 20:36

score 5 · Accepted Answer · answered Dec 27 '10 at 20:10

Those symbols refer to certain bitwise operations.

>> Right shift
<< Left shift
|  Bitwise OR
&  Bitwise AND

Read up on the linked Wikipedia page for more information on what they do.

See here for why JSLint warns on these operations. It largely has to do with efficiency (i.e., JavaScript uses floating point numbers internally and it's inefficient to cast to integers and back with bitwise operators).

Right shift and left shift can be replaced with dividing by and multiplying by 2, respectively.

score 0 · Answer 2 · answered Dec 27 '10 at 20:10

0

This gets asked all the time, but it's difficult for some to find the right word to search on.

Those are bitwise operators.

answered Dec 27 '10 at 20:10

zzzzBov

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score 0 · Answer 3 · answered Dec 27 '10 at 20:12

0

JSLint validates it fine for me when I declare the c and utftext variables. I don't see it complaining about any of these operators.

answered Dec 27 '10 at 20:12

Pekka

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not if you've "the Good Parts" turned on. – Couto Dec 27 '10 at 20:49

Meaning of >>, <<, | and & in JavaScript

3 Answers3

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