I have some data in a node app which are numbers in string format. I'm trying to parse them and round off to 3 decimals by parseFloat(num).toFixed(3). Since the numbers are very large, it is automatically converting them to scientific notation (eg 2.0210702881736412e+37). I switched to using parseInt(), Number() but nothing works. How do I get around this?
The data object is very huge so I'm skeptical to use a custom converter function which converts the exponential form to decimal, since it might impact performance.
Use BigInt
const num = BigInt(2.0210702881736412e+37);
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt
BigInt values are similar to Number values in some ways, but also differ in a few key matters: A BigInt value cannot be used with methods in the built-in Math object and cannot be mixed with a Number value in operations; they must be coerced to the same type. Be careful coercing values back and forth, however, as the precision of a BigInt value may be lost when it is coerced to a Number value.
How you use BigInt for it: BigInt(n).toString();
const num = BigInt(2.0210702881736412e+37);
// 20210702881736411847466551731631947776n
const strNum = num.toString();
// 20210702881736411847466551731631947776
Edit, additional info
Bigint library (or also the builtin data type) can only handle integers. I think try the JavaScript numeric operation library seems to be the fastest way to calculate the decimal point. A bignumber library typically works with arbitrary-precision floating-point numbers. There are several recommended libraries. bignumber.js Or BigNumber