Extremely large numbers in javascript

I'm working on the Project Euler problems (currently question 13).

For this question I have to find the first 10 digits of the sum of 100 numbers all of a size similar to this:

91,942,213,363,574,161,572,522,430,563,301,811,072,406,154,908,250

I think I could use something like Java's BigInteger, but I started solving the problems in JavaScript (I'm trying to boost my js abilities for work), and I would like to continue using it, even to solve this problem.

I'd like to stick to pure JS if possible.

Solution 1:

You are going to need a javascript based BigInteger library. There are many to choose from. Here is one https://github.com/peterolson/BigInteger.js

You can use it like this

var n = bigInt("91942213363574161572522430563301811072406154908250")
    .plus("91942213363574161572522430563301811072406154908250");

Solution 2:

Javascript recently got a new primitive data type BigInt (stage 4 proposal as of January 2020). https://github.com/tc39/proposal-bigint

Chrome, Firefox and few other browsers have started supporting this in newer versions (check compatibility here), while other browsers are still implementing it.

https://developers.google.com/web/updates/2018/05/bigint

Basically it can be declared using either literals like

var a = 1n;

or

var b = BigInt('22222222222222222222222222222222');

Math operators don't do auto conversion between BigInt and Number, so

1 + 1n

will throw an error.