Extremely large numbers in javascript

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");

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.

Surprisingly, sticking all the values in an array and adding them all together and just taking the first 10 digits worked. I must have had a typo somewhere in my code when it didn't work before.

I'm sure that doing something this simple wouldn't work in all cases (like those @AlexMcmillan and @zerkms have been debating about). I think the safest bet is the BigInteger library mentioned by @bhspencer, but it seems like adding the first x significant digits with y digits as a buffer might also be worth a shot in some cases.