How to store a byte array in Javascript

Question

I'm going to be storing a large array of byte values (most likely over a million) in Javascript. If I use a normal array with normal numbers, that will take 8 MB, because numbers are stored as IEEE doubles, but if I can store it as bytes, it will be only 1 MB.

I'd like to avoid wasting that much space for obvious reasons. Is there a way to store bytes as bytes instead of doubles? Browser compatibility isn't an issue for me, as long as it works in Chrome. This is in HTML5, if that makes a difference.

Answer 1

By using typed arrays, you can store arrays of these types:

Type	Value Range	Size(bytes)
Int8Array	-128 to 127	1
Uint8Array	0 to 255	1
Uint8ClampedArray	0 to 255	1
Int16Array	-32768 to 32767	2
Uint16Array	0 to 65535	2
Int32Array	-2147483648 to 2147483647	4
Uint32Array	0 to 4294967295	4
Float32Array	-3.4E38 to 3.4E38	4
Float64Array	-1.8E308 to 1.8E308	8
BigInt64Array	-2^63 to 2^63 - 1	8
BigUint64Array	0 to 2^64 - 1	8

Demo in Stack Snippets & JSFiddle

var array = new Uint8Array(100); array[42] = 10; console.log(array[42]);

Answer 2

var array = new Uint8Array(100);     array[10] = 256; array[10] === 0 // true 

I verified in firefox and chrome, its really an array of bytes :

var array = new Uint8Array(1024*1024*50);  // allocates 50MBytes