Converting string into number, result in a different number

Question

When I try to convert a bigint passed from php, into a integer in nodejs, the result is always different, I couldn't figure out what's wrong with it.

> var a = parseInt('135601920000000040', 10);
undefined
> a
135601920000000030
> var a = parseFloat('135601920000000040');
undefined
> a
135601920000000030
> var n = Number('135601920000000040');
undefined
> n
135601920000000030

Not only node.js, it also happen to js interpreter in Firefox

have you tried different numbers or only 135601920000000040? if you tried different, what are the results? can you see any pattern that may lead to a solution? — Chris
– Chris, Commented Mar 13, 2012 at 10:01

Just_Mad · Accepted Answer · 2012-03-13 10:17:54Z

3

The Number type in javascript is represented as double precision floating point, so, it a value passed to parseInt, parseFloat etc is more than 9007199254740992 (ECMAScirpt Numbers specification) it is rouned to fit the Number type.

edited Mar 13, 2012 at 10:17

answered Mar 13, 2012 at 10:06

Just_Mad

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1 Comment

Leric Over a year ago

Thanks, I got it. javascript don't have a 64bit integer, same as php

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