RangeError: invalid array length

The JavaScript exception "Invalid array length" occurs when specifying an array length that is either negative, a floating number or exceeds the maximum supported by the platform (i.e. when creating an Array or ArrayBuffer, or when setting the length property).

The maximum allowed array length depends on the platform, browser and browser version. For Array the maximum length is 2³²-1. For ArrayBuffer the maximum is 2³¹-1 (2GiB-1) on 32-bit systems. From Firefox version 89 the maximum value of ArrayBuffer is 2³³ (8GiB) on 64-bit systems.

Note: Array and ArrayBuffer are independent data structures (the implementation of one does not affect the other).

Message

RangeError: invalid array length (V8-based & Firefox)
RangeError: Array buffer allocation failed (V8-based)
RangeError: Array size is not a small enough positive integer. (Safari)

Error type

RangeError

What went wrong?

An invalid array length might appear in these situations:

Creating an Array or ArrayBuffer with a negative length, or setting a negative value for the length property.
Creating an Array or setting the length property greater than 2³²-1.
Creating an ArrayBuffer that is bigger than 2³¹-1 (2GiB-1) on a 32-bit system, or 2³³ (8GiB) on a 64-bit system.
Creating an Array or setting the length property to a floating-point number.
Before Firefox 89: Creating an ArrayBuffer that is bigger than 2³¹-1 (2GiB-1).

If you are creating an Array, using the constructor, you probably want to use the literal notation instead, as the first argument is interpreted as the length of the Array.

Otherwise, you might want to clamp the length before setting the length property, or using it as argument of the constructor.

Examples

Invalid cases

new Array(Math.pow(2, 40));
new Array(-1);
new ArrayBuffer(Math.pow(2, 32)); // 32-bit system
new ArrayBuffer(-1);

const a = [];
a.length = a.length - 1; // set the length property to -1

const b = new Array(Math.pow(2, 32) - 1);
b.length = b.length + 1; // set the length property to 2^32
b.length = 2.5; // set the length property to a floating-point number

const c = new Array(2.5); // pass a floating-point number

Valid cases

[Math.pow(2, 40)]; // [ 1099511627776 ]
[-1]; // [ -1 ]
new ArrayBuffer(Math.pow(2, 31) - 1);
new ArrayBuffer(Math.pow(2, 33)); // 64-bit systems after Firefox 89
new ArrayBuffer(0);

const a = [];
a.length = Math.max(0, a.length - 1);

const b = new Array(Math.pow(2, 32) - 1);
b.length = Math.min(0xffffffff, b.length + 1);
// 0xffffffff is the hexadecimal notation for 2^32 - 1
// which can also be written as (-1 >>> 0)

b.length = 3;

const c = new Array(3);

Docs

Docs4dev

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