swift-url-check

Fast and robust URL validator

Why?

This library provides a faster and more robust URL validation compared to is-url-superb. It uses optimized validation logic with early returns and efficient regex patterns to achieve better performance.

Features

• ⚡ Fast - Optimized for performance with early validation checks
• 🛡️ Robust - Comprehensive validation including hostname, protocol, and structure checks
• 🎯 Flexible - Configurable options for different use cases
• 📦 Small - Zero dependencies
• 🔧 TypeScript - Full TypeScript support with type definitions
• 🌐 ESM & CommonJS - Supports both module systems

Install

npm install swift-url-check

Usage

import isUrl from 'swift-url-check';

isUrl('https://opensly.in');
//=> true

isUrl('not a url');
//=> false

isUrl('example.com');
//=> false

isUrl('example.com', { lenient: true });
//=> true

CommonJS

This package is ESM-only. For CommonJS support, use dynamic import:

const isUrl = (await import('swift-url-check')).default;

isUrl('https://example.com');
//=> true

TypeScript

import isUrl, { IsUrlOptions } from 'swift-url-check';

const options: IsUrlOptions = {
  lenient: true,
  allowLocal: false
};

isUrl('https://example.com', options);
//=> true

API

isUrl(string, options?)

Returns true if the string is a valid URL, false otherwise.

string

Type: string

The string to validate as a URL.

options

Type: object

lenient

Type: boolean
Default: false

Allow URLs without protocol. When true, strings like "example.com" will be considered valid.

isUrl('example.com');
//=> false

isUrl('example.com', { lenient: true });
//=> true

allowLocal

Type: boolean
Default: true

Allow localhost and local IP addresses. When false, localhost, 127.0.0.1, 192.168.x.x, 10.x.x.x, etc. will be rejected.

isUrl('http://localhost:3000');
//=> true

isUrl('http://localhost:3000', { allowLocal: false });
//=> false

protocols

Type: string[]
Default: ['http:', 'https:']

Specify which protocols are considered valid.

isUrl('ftp://example.com');
//=> false

isUrl('ftp://example.com', { protocols: ['ftp:', 'ftps:'] });
//=> true

Validation Rules

The validator checks for:

• Valid protocol format
• Proper hostname structure
• No whitespace in URLs
• Valid domain parts (labels)
• Proper TLD format
• IPv4 and IPv6 support
• Port number validation
• Path, query, and hash support

Testing

Run tests:

npm test

Run tests with coverage:

npm run test:coverage

Watch mode for development:

npm run test:watch

The library has comprehensive test coverage with 47 test cases covering:

• Basic URL validation
• URL components (paths, query strings, hash fragments, ports)
• Subdomains and IP addresses
• All configuration options
• Edge cases and error conditions

Performance

Run the benchmark:

npm run benchmark

Compare with is-url-superb:

npm run benchmark:compare

Benchmark Results

1.89x faster than is-url-superb (88.5% improvement)

swift-url-check:  3,234,110 ops/sec (0.309µs per operation)
is-url-superb:    1,715,301 ops/sec (0.583µs per operation)

This library is optimized for speed with:

• Early type checking
• Fast-path validations before URL parsing
• Efficient regex patterns
• Minimal allocations

Comparison with is-url-superb

Feature	swift-url-check	is-url-superb
Performance	⚡ 1.89x Faster	Standard
TypeScript	✅ Built-in	❌ Requires @types
ESM Support	✅ ESM-only	✅ ESM-only
Local URL Control	✅ Configurable	❌ No option
Protocol Control	✅ Configurable	❌ Fixed
Dependencies	0	1 (is-url)

License

MIT