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Showing content from https://stackoverflow.com/questions/2373791/bitshift-in-javascript below:

bit shift - Bitshift in javascript

I've got a really big number: 5799218898. And want to shift it right to 13 bits.
So, windows-calculator or python gives me:

5799218898 >> 13 | 100010100100001110011111100001 >> 13
70791            | 10001010010000111

As expected.

But Javascript:

5799218898 >> 13 | 100010100100001110011111100001 >> 13
183624           | 101100110101001000

I think it because of internal integer representation in javascript, but cannot find anything about that.

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asked Mar 3, 2010 at 18:13

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In ECMAScript (Javascript) bitwise operations are always in 32-bit. Therefore 5799218898 is chopped into 32-bit which becomes 1504251602. This integer >> 13 gives 183624.

In Python they are arbitrary-length integers. So there's no problem.

(And the numbers in Windows calculator are 64-bit, enough to fit 5799218898.)

(And the correct answer should be 707912.)

answered Mar 3, 2010 at 18:16

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If you have a modern browser, you might want to use bigint for values greater than 32-bit signed. They were introduced in the 11-th Edition of ECMAScript Language back in 2020.

It is stated, you also find a browser compatibility table:

Bitwise operators are supported as well, except >>> (zero-fill right shift), as every BigInt value is signed. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt

You can do the following, tested for example in Chrome:

> Number(BigInt(5799218898) >> BigInt(13))
<- 707912

answered Jun 27, 2021 at 15:22

As Nicholas Zakas states:

Even though JavaScript numbers are technically stored in 64-bits, integer values are treated as if they’re 32 bits whenever bitwise operators are involved.

answered Mar 3, 2010 at 18:23

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The number you have (5799218898) is beyond 32 bits. You didn't mention the JavaScript engine you're testing with, but it's very likely that it is 32-bit.

To test, trim the "5" at the beginning of your number so that you fall inside the 32-bit boundary. Then your shift should work fine.

answered Mar 3, 2010 at 18:17

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