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require-array-sort-compare

Require Array#sort and Array#toSorted calls to always provide a compareFunction.

💭

This rule requires type information to run.

When called without a compare function, Array#sort() and Array#toSorted() 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 sort methods that do not provide a compare argument.

.eslintrc.cjs
module.exports = {
  "rules": {
    "@typescript-eslint/require-array-sort-compare": "error"
  }
};

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Examples​

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

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

array.sort();

// String arrays should be sorted using `String#localeCompare`.
stringArray.sort();
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Options​

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 }];

ignoreStringArrays​

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

const one = 1;
const two = 2;
const three = 3;
[one, two, three].sort();
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When Not To Use It​

If you intentionally want your arrays to be always sorted in a string-like manner, you can turn this rule off safely.

Type checked lint rules are more powerful than traditional lint rules, but also require configuring type checked linting. See Performance Troubleshooting if you experience performance degredations after enabling type checked rules.

Resources​