How to convert BigInt to Number in JavaScript?

Turns out it's as easy as passing it to the Number constructor:

const myBigInt = BigInt(10);  // `10n` also works
const myNumber = Number(myBigInt);

Of course, you should bear in mind that your BigInt value must be within [Number.MIN_SAFE_INTEGER, Number.MAX_SAFE_INTEGER] for the conversion to work properly, as stated in the question.

You can use parseInt or Number

const large =  BigInt(309);
const b = parseInt(large);
console.log(b);
const n = Number(large);
console.log(n);