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Require Array#sort calls to always provide a compareFunction.


This rule requires type information to run.

When called without a compare function, Array#sort() converts all non-undefined array elements into strings and then compares said strings based off their UTF-16 code units [ECMA specification].

The result is that elements are sorted alphabetically, regardless of their type. For example, when sorting numbers, this results in a "10 before 2" order:

[1, 2, 3, 10, 20, 30].sort(); //→ [1, 10, 2, 20, 3, 30]

This rule reports on any call to the Array#sort() method that doesn't provide a compare argument.

module.exports = {
"rules": {
"@typescript-eslint/require-array-sort-compare": "error"
Try this rule in the playground ↗


This rule aims to ensure all calls of the native Array#sort method provide a compareFunction, while ignoring calls to user-defined sort methods.

const array: any[];
const stringArray: string[];


// String arrays should be sorted using `String#localeCompare`.


This rule accepts the following options

type Options = [
/** Whether to ignore arrays in which all elements are strings. */
ignoreStringArrays?: boolean;

const defaultOptions: Options = [{ ignoreStringArrays: true }];


Examples of code for this rule with { ignoreStringArrays: true }:

const one = 1;
const two = 2;
const three = 3;
[one, two, three].sort();

When Not To Use It

If you understand the language specification enough, and/or only ever sort arrays in a string-like manner, you can turn this rule off safely.