Parse Float has a rounding limit? How can I fix this?

问题

I set up a system that parses a compact data string into JSON. I'm using a 19 digit number to store ids. Unfortunately any number greater than 17 digits, parseFloat() rounds the last few digits.

This breaks the whole data string. Can I fix this?

For example 8246295522085275215 gets turned into 8246295522085276000. Why is this?

http://jsfiddle.net/RobertWHurst/mhZ7Q/

回答1:

JavaScript has only one numeric type, which is an IEEE 754 double precision floating-point. That means, you have a maximum of 52 bits of precision, which is a bit more than 15 decimal places.

If you need more precision than that, you have to use a bignum library or work with strings.

回答2:

Numbers in JavaScript lose precision if they are higher than a certain value.

According to http://www.hunlock.com/blogs/The_Complete_Javascript_Number_Reference, integers are only reliable up to 15 digits (9 * 10^15 to be exact).

回答3:

Try one of these 1. Use a string 2. Split your number in two and save the smaller parts to an array 3. Bignum library 4. Use a smaller number if you can

来源：https://stackoverflow.com/questions/7988827/parse-float-has-a-rounding-limit-how-can-i-fix-this