Javascript display really big numbers rather than displaying xe+n

Question

I have javascript code that often outputs very big numbers, that I would like to be displayed fully rather than getting a value such as 2.7934087356437704e+56 I'd like it to display the entire number. Is it possible to make this happen in JS?

Take a look at the answer here http://stackoverflow.com/questions/4170633/opposite-of-number-toexponential-in-js — TommyBs, Apr 17 '13 at 17:56
Do you really need 60-digit precision numbers? Who is supposed to read them, what are you computing with them? — Bergi, Apr 17 '13 at 18:06

nullability · Accepted Answer · 2013-04-17T19:06:21.600

With such a large number, you will lose precision in Javascript. The exponential form it returns is the most precise Javascript can represent. However, if you do not care about the loss of precision and just want a string of the expanded number, you can use your own function to do this. I couldn't find a method that will do this natively so you have to add it in yourself.

I found this snippet which will do that for you by Jonas Raoni Soares Silva:

String.prototype.expandExponential = function(){
    return this.replace(/^([+-])?(\d+).?(\d*)[eE]([-+]?\d+)$/, function(x, s, n, f, c){
        var l = +c < 0, i = n.length + +c, x = (l ? n : f).length,
        c = ((c = Math.abs(c)) >= x ? c - x + l : 0),
        z = (new Array(c + 1)).join("0"), r = n + f;
        return (s || "") + (l ? r = z + r : r += z).substr(0, i += l ? z.length : 0) + (i < r.length ? "." + r.substr(i) : "");
    });
};

A usage example would be:

> var bignum = 2.7934087356437704e+56;
> (bignum+'').expandExponential();
"279340873564377040000000000000000000000000000000000000000"

You have to cast the number to a string first, hence the +''

If you really need exact precision you can try using a library like Big Number or javascript-bignum.

:) the precision doesn't matter too much, I just need it to be the right length in terms of number of digits. Thanks! — Seb, Apr 17 '13 at 18:22

score 1 · Answer 2 · answered Apr 17 '13 at 17:53

1

In JavaScript all numbers are floating point numbers so you don't have absolute precision.

answered Apr 17 '13 at 17:53

Halcyon

57,230
10
89
128

So it is not possible to accurately display the number to ~250 digits? – Seb Apr 17 '13 at 17:59
@Seb, you need to use a third-party library dealing with bignums. There are quite a few available. – Fabien Apr 17 '13 at 18:03
3

@Fabien, could you point me to any? – Seb Apr 17 '13 at 18:21

Javascript display really big numbers rather than displaying xe+n

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