BigInt and Numeric Separators

Use BigInt for whole numbers past Number’s safe range, and underscores to make large literals readable.

Number cannot represent every integer exactly above Number.MAX_SAFE_INTEGER (9_007_199_254_740_991). BigInt literals end with n. You cannot mix BigInt and Number with + without converting. 

Results appear here.

Enter digits larger than the safe integer limit to see the difference.

Important JavaScript

const safeMax = Number.MAX_SAFE_INTEGER; // 9_007_199_254_740_991
const asNumber = 9007199254740993;       // loses exactness
const asBigInt = 9007199254740993n;      // exact

const million = 1_000_000;
const budget = 12_500_000n;

// Mixed arithmetic throws — convert first:
Number(asBigInt) + 1;
asBigInt + BigInt(1);