Strings

How to Check if String Contains Substring

Use .includes() to check for substring presence

Quick Answer (2024 ES6+ Way)

javascript

const text = 'Hello World';
const hasWorld = text.includes('World');
console.log(hasWorld); // true

Live Example

javascript

const email = '[email protected]';

// Check if valid email format (simplified)
const isValid = email.includes('@') && email.includes('.');
console.log(`Valid: ${isValid}`);

// Case-insensitive search
const text = 'JavaScript is awesome';
const hasJS = text.toLowerCase().includes('javascript');
console.log(`Has JS: ${hasJS}`);

Common Variations

Check Start/End

javascript

const url = 'https://example.com';
url.startsWith('https'); // true
url.endsWith('.com'); // true

Find Position

javascript

const index = text.indexOf('World');
// Returns -1 if not found, position if found

❌ Don't Do This (Outdated Way)

Avoid indexOf() !== -1 pattern

javascript

// DON'T DO THIS
if (text.indexOf('World') !== -1) {
  // found
}

Browser Support

✓ Works in all modern browsers (ES2015+)

#strings#includes#search