How to convert a String to long in javascript?

Question

I have a millisecond timestamp that I need to convert from a string to long. JavaScript has a parseInt but not a parseLong. So how can I do this?

To expand on my question slightly: given that apparently JavaScript doesn't have a long type, how can I do simple arithmetic with longs that are initially expressed as strings? E.g subtract one from the other to get a time delta?

Javascript doesn't have a parseLong because it doesn't have a long. (Some old-timer may be able to tell you a story about why Javascript never got a long.) — awm
– awm, Commented Mar 27, 2011 at 14:58
So it's not possible to do arithmetic with longs in javascript?? — Richard H
– Richard H, Commented Mar 27, 2011 at 15:02

Russ Cam · Accepted Answer · 2011-03-27 15:08:11Z

136

JavaScript has a Number type which is a 64 bit floating point number*.

If you're looking to convert a string to a number, use

either parseInt or parseFloat. If using parseInt, I'd recommend always passing the radix too.
use the Unary + operator e.g. +"123456"
use the Number constructor e.g. var n = Number("12343")

*there are situations where the number will internally be held as an integer.

edited Mar 27, 2011 at 15:08

answered Mar 27, 2011 at 15:02

Russ Cam

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3 Comments

Charlie Schliesser Over a year ago

So, if I wanted to parse the string "71157133118211271" to a number/long in Javascript, how would I go about that? Split it into 16-digit strings, parse each of them separately, and concatenate them together?

Russ Cam Over a year ago

@CharlieS You use a library like javascript-bignum (github.com/jtobey/javascript-bignum) or BigInt.js (leemon.com/crypto/BigInt.html) that provides support for large numbers.

user2447290 Over a year ago

be careful with zero to left side

Jamey · Accepted Answer · 2021-03-03 17:29:57Z

10

BigInt("1274836528318476135")

answered Mar 3, 2021 at 17:29

Jamey

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1 Comment

davetapley Over a year ago

See also stackoverflow.com/questions/55646698/base-36-to-bigint

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