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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"
}
};

Try this rule in the playground ↗

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 Troubleshooting > Linting with Type Information > Performance if you experience performance degredations after enabling type checked rules.

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