#prefer-set-size

#Configuration

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

export default defineConfig([
  unicornPlugin.configs.recommended,
  {
    rules: {
      'unicorn/prefer-set-size': 'error',
    },
  },
]);

Prefer using Set#size instead of Array#length.

Converting a Set into an array solely to read its length performs unnecessary work. Use its size property directly.

#Examples

// Incorrect
const uniqueCount = [...new Set(userIds)].length;

// Correct
const uniqueCount = new Set(userIds).size;

// Incorrect
const count = Array.from(items).length;

// Correct
const count = items.size;

#Original Documentation

• eslint-plugin-unicorn: prefer-set-size
• Source code