Javascript magic number 79753741930607500

Question

Is there any way to increase this number?

console.log(79753741930607500+1) // 79753741930607500
console.log(79753741930607499+3) // 79753741930607500

upd:

zip encrypt/decrypt functions use 64bit numbers:

keys[0] = 305419896;
keys[1] = 591751049;
keys[2] = 878082192;

this.update_keys=function(c){
    keys[0]=crc32.crc32(keys[0],c);
    keys[1]=(((keys[1]+(keys[0]&0xff))*0x08088405+1)& 0xffffffff) >>>0;
    keys[2] = crc32.crc32(keys[2], keys[1] >>> 24);
};

keys[1] intermediate calculation may be more 79753741930607500.

exists universal solution to nodejs and browsers can use 64bit integers?

@LynnCrumbling yes. But the javavascript numeric data type has already been explained. OP should tell us what his actual question is if he wants it answered. — John Dvorak, Jun 06 '14 at 12:40
@Sirko console.log(Number.MAX_VALUE); 1.7976931348623157e+308 — askovpen, Jun 06 '14 at 12:41
@askovpen There is a difference between `MAX_VALUE`, which is the biggest number you can use, and the number from my link, which is the largest integer, you can use without loss of precision. — Sirko, Jun 06 '14 at 12:46

Ben Fortune · Answer 1 · 2014-06-06T12:51:32.723

3

Since the question is tagged node.js this is possible using the node-bigint module.

Install with

npm install bigint

Usage:

var bigint = require('bigint');

console.log(bigint('79753741930607500').add(3)); //<BigInt 79753741930607503>

Though do note, there's no way to keep it as an integer and it will be returned as a bigint string or you can convert it to a string with the method .toString(). If you do try and return it as an integer, you will lose precision or it will return infinity.

edited Jun 06 '14 at 12:51

answered Jun 06 '14 at 12:45

Ben Fortune

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Is that a default module? Is there an official documentation for it? – John Dvorak Jun 06 '14 at 12:46
@JanDvorak It's an external module, it's linked in the answer. – Ben Fortune Jun 06 '14 at 12:47
+1 Nice. Gives the OP an answer to their original question of how they can store and increment the number. – Lynn Crumbling Jun 06 '14 at 12:48
exists universal solution for nodejs and browsers? – askovpen Jun 06 '14 at 14:44
If you'd taken any time to research, google would've brought you to [this](https://github.com/jtobey/javascript-bignum). – Ben Fortune Jun 06 '14 at 14:48
@BenFortune `javascript-bignum` don't have `bitwise and` – askovpen Jun 06 '14 at 14:58
What are you talking about? Bitwise operators are a part of javascript. – Ben Fortune Jun 06 '14 at 15:00
@BenFortune for bigint. like https://github.com/substack/node-bigint#andn – askovpen Jun 06 '14 at 15:54

Javascript magic number 79753741930607500

1 Answers1