what is the max array size in Javascript and which arrays to use [duplicate]

Question

I wanted t create a large array in Javascript and wrote the following code but it did not work due to OOM

let N = 125000000;
let numbers = [];
for (let i = 0; i < N; i++) {
    numbers[i] = Math.round(Math.random()*10000);
}

Then I wrote "let numbers = new Array(N);" instead, which worked for the N (125000000) but did not work with larger N (200000000). Then I used Uint32Array, which worked for even larger N. It worked up to N = 2^31-1. Is there any limit on size in [], new Array(size), Uint32Array in Javascript? I guess the max size o Uint32Array is 2^31-1. I also want to know why new Array(N) has higher limit than []. Thank you

I guess If you're putting numbers into Array literal ([]) or Array Object (new Array(size)) they are stored as signed 64-bit Floating Point number - 64bits and If you're putting numbers into UInt32Array they are stored as unsigned 32-bit int numbers - 32bits. So, RAM-usage is twice less than in the first case. — Ihor Sakailiuk
– Ihor Sakailiuk, Commented May 27, 2019 at 17:58

Nick · Accepted Answer · 2019-05-27 20:24:20Z

2

NodeJS follows the ECMAScript specification, that is implemented via the V8 engine.

The maximum you can fit inside is 4,294,967,295 = 4.29 billion elements.

You ran out of memory because V8 sets a memory limit, you can bypass this limit by invoking Node with 'max-old-space-size' parameter, like so:

node --max-old-space-size=1024 yourscript.js

Where 1024 is 1GB, 2048 2GB and so goes on.

answered May 27, 2019 at 20:24

Nick

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