#no-boolean-sort-comparator

#Configuration

import { defineConfig, unicornPlugin } from '@rslint/core';

export default defineConfig([
  unicornPlugin.configs.recommended,
  {
    rules: {
      'unicorn/no-boolean-sort-comparator': 'error',
    },
  },
]);

#Rule Details

Sorting comparators must return a negative number, zero, or a positive number. A boolean comparator can only produce 0 or 1 after conversion to a number, so it cannot place the first value before the second.

The rule checks sort() and toSorted() on arrays and typed arrays. It recognizes concise callbacks, functions with a single return statement, explicit boolean return types, and references to known boolean functions.

Examples of incorrect code

array.sort((a, b) => a > b);
array.sort((a, b) => a.score >= b.score);
strings.toSorted((a, b) => a === b);

Examples of correct code

array.sort((a, b) => a - b);
array.sort((a, b) => a.score - b.score);
strings.toSorted((a, b) => a.localeCompare(b));

#Suggestions

For simple comparisons between the two parameters or matching properties, the rule can suggest subtraction in the editor. Review the suggested order before applying it. The rule has no automatic fix.

#Options

This rule has no options.

#Differences from upstream

rslint withholds the subtraction suggestion when it recognizes a string or BigInt operand, including through a generic constraint such as T extends bigint. For example, [-2n, -1n].sort((a, b) => a > b) and BigInt64Array.of(1n, 2n).sort((a, b) => a > b) still produce diagnostics. Use localeCompare() for strings. For BigInts, return a number with a < b ? -1 : a > b ? 1 : 0.

rslint also withholds the suggestion if converting the comparator to an arrow would change what its this, arguments, or function name refers to, or if the rewrite would discard a return type assertion or leave a boolean JSDoc return type in place. Update the comparator body and any return type together.

#Original Documentation

• eslint-plugin-unicorn: no-boolean-sort-comparator
• Source code