Why does console.log(10150141932135203) print 10150141932135204 in both Firefox and Chrome and how to I deal with large integer values like these?

Question

I was trying to figure out why one of our clients on Facebook was having issues and I traced it to the number 10150141932135203 turning into 10150141932135204 giving us rather unexpected results.

$ node
> 10150141932135203
10150141932135204
> 10150141932135204
10150141932135204
> 10150141932135205
10150141932135204
> 10150141932135206
10150141932135206
> 10150141932135207
10150141932135208
> 10150141932135208
10150141932135208
> 10150141932135209
10150141932135208
> 10150141932135210
10150141932135210

How can I deal with integer numbers of this size?

Answer 1

If the numbers are bigger than what the IEEE 754 spec allows (2 ⁵³ ), they will lose precision as your examples demonstrate.

You could use a Binary Coded Decimal library for JavaScript, eg BCMathJs .

This, of course, is only applicable if you need to perform arithmetic on the numbers. If not, keep them as strings.