@devt110103/utils-js

A comprehensive utility library for JavaScript and TypeScript with full type support.

Installation

npm install @devt110103/utils-js

Features

• ✅ Full TypeScript Support - Complete type definitions for perfect IntelliSense
• 🌍 Number Formatting - Locale-aware number formatting with currency, percent, and custom options
• 📅 Date Formatting - Comprehensive date formatting with dayjs integration
• 📦 Zero Configuration - Works out of the box with sensible defaults
• 🔧 Highly Customizable - Extensive options for advanced use cases

Usage

Number Formatting

import { formatNumber } from '@devt110103/utils-js';

// Basic usage with locale
formatNumber(1234.56, 'vi-VN');        // "1.234,56"
formatNumber(1234.56, 'en-US');        // "1,234.56"

// Currency formatting
formatNumber(1234.56, {
  style: 'currency',
  currency: 'VND',
  locale: 'vi-VN'
});  // "1.235 ₫"

formatNumber(1234.56, {
  style: 'currency',
  currency: 'USD',
  locale: 'en-US'
});  // "$1,234.56"

// Percentage formatting
formatNumber(0.1234, {
  style: 'percent',
  minimumFractionDigits: 2
});  // "12.34%"

// Custom decimal places
formatNumber(1234.56789, {
  minimumFractionDigits: 2,
  maximumFractionDigits: 3
});  // "1,234.568"

Date Formatting

import { formatDate } from '@devt110103/utils-js';

const date = new Date('2025-08-01T14:30:00');

// Basic formats
formatDate(date, 'YYYY-MM-DD');              // "2025-08-01"
formatDate(date, 'DD/MM/YYYY');              // "01/08/2025"
formatDate(date, 'MM/DD/YYYY');              // "08/01/2025"

// With time
formatDate(date, 'YYYY-MM-DD HH:mm:ss');     // "2025-08-01 14:30:00"
formatDate(date, 'DD/MM/YYYY h:mm A');       // "01/08/2025 2:30 PM"

// Long formats
formatDate(date, 'MMMM D, YYYY');            // "August 1, 2025"
formatDate(date, 'dddd, MMMM D, YYYY');      // "Friday, August 1, 2025"

// ISO formats
formatDate(date, 'YYYY-MM-DDTHH:mm:ss');     // "2025-08-01T14:30:00"

// Custom format (any dayjs format)
formatDate(date, 'YYYY年MM月DD日');           // "2025年08月01日"

TypeScript Support

This library is written in TypeScript and provides full type definitions. When you install the package, you'll get:

• IntelliSense - Auto-completion for all function parameters
• Type Safety - Compile-time checking for correct usage
• Documentation - Hover tooltips with parameter descriptions
• Format Suggestions - Auto-complete for date format strings

Example with TypeScript

import { formatNumber, formatDate } from '@devt110103/utils-js';

// TypeScript will provide auto-completion for format strings
const formatted = formatDate(new Date(), 'YYYY-MM-DD'); // ✅ Suggested formats
const number = formatNumber(1234.56, {
  style: 'currency', // ✅ Auto-complete: 'decimal' | 'currency' | 'percent' | 'unit'
  currency: 'USD'    // ✅ Type-safe
});

API Reference

formatNumber(value, options?)

Formats a number with locale and style options.

Parameters:

• value: number - The number to format
• options?: string | object - Locale string or formatting options

Options Object:

• locale?: string - BCP 47 language tag (e.g., 'en-US', 'vi-VN')
• style?: 'decimal' | 'currency' | 'percent' | 'unit' - Number formatting style
• currency?: string - Currency code (e.g., 'USD', 'VND') - required when style is 'currency'
• unit?: string - Unit identifier (e.g., 'kilometer') - required when style is 'unit'
• minimumFractionDigits?: number - Minimum number of decimal places
• maximumFractionDigits?: number - Maximum number of decimal places
• useGrouping?: boolean - Whether to use grouping separators

formatDate(date, format)

Formats a date using dayjs with comprehensive format options.

Parameters:

• date: Date - The date to format
• format: string - Format string (with auto-completion for common patterns)

Common Format Patterns:

• YYYY-MM-DD - ISO date format
• DD/MM/YYYY - European date format
• MM/DD/YYYY - US date format
• MMMM D, YYYY - Long format with month name
• dddd, MMMM D, YYYY - Full format with day name
• And many more...

License

MIT

Author

DevT (@devt110103)