#prefer-reduce-type-parameter

#Configuration

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

export default defineConfig([
  ts.configs.recommended,
  {
    rules: {
      '@typescript-eslint/prefer-reduce-type-parameter': 'error',
    },
  },
]);

#Rule Details

Enforce using type parameters for Array#reduce instead of type assertions on the initial value. When calling Array#reduce, it is common to use a type assertion (as) on the initial value to specify the result type. However, Array#reduce accepts a type parameter that achieves the same result in a cleaner way without requiring a type assertion.

Examples of incorrect code for this rule:

[1, 2, 3].reduce(
  (acc, val) => ({ ...acc, [val]: true }),
  {} as Record<number, boolean>,
);
['a', 'b'].reduce((acc, val) => [...acc, val], [] as string[]);

Examples of correct code for this rule:

[1, 2, 3].reduce<Record<number, boolean>>(
  (acc, val) => ({ ...acc, [val]: true }),
  {},
);
['a', 'b'].reduce<string[]>((acc, val) => [...acc, val], []);

#Original Documentation

• typescript-eslint prefer-reduce-type-parameter