Check if String contains any Letter in JavaScript

Check if String contains any Letter #

To check if a string contains any letter, use the test() method with the following regular expression /[a-zA-Z]/. The test method will return true if the string contains at least one letter and false otherwise.

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function containsAnyLetter(str) {
  return /[a-zA-Z]/.test(str);
}

console.log(containsAnyLetter('abc123')); // 👉️ true
console.log(containsAnyLetter('ABC')); // 👉️ true
console.log(containsAnyLetter('123')); // 👉️ false
console.log(containsAnyLetter(' ')); // 👉️ false

if (containsAnyLetter('hello')) {
  console.log('✅ string contains a letter');
} else {
  console.log('⛔️ string does NOT contain a letter');
}

We used the RegExp.test method to check if a string contains at least 1 letter.

The test method returns true if the regular expression is matched in the string and false otherwise.

The forward slashes / / mark the start and end of the regular expression.

The square brackets [] are called a character class. In the character class we match 2 ranges:

• all lowercase letters a-z
• all uppercase letters A-Z

If you ever need help reading a regular expression, bookmark this regex cheatsheet from MDN. It's by far the best one out there.

Instead of using 2 ranges for lowercase and uppercase letters, we can also perform a case insensitive match, by using the i flag.

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function containsAnyLetter(str) {
  // 👇️ using the `i` flag
  return /[a-z]/i.test(str);
}

console.log(containsAnyLetter('A1')); // 👉️ true
console.log(containsAnyLetter('! !')); // 👉️ true

if (containsAnyLetter('abc123')) {
  console.log('✅ string contains a letter');
} else {
  console.log('⛔️ string does NOT contain a letter');
}

In this regular expression, we use the i flag for case insensitive search, instead of using the range of uppercase letters A-Z.

Further Reading #

• Check if String contains Special Characters in JavaScript
• Check if String contains Whitespace in JavaScript