JS RegExp Classes

JavaScript RegExp Character Classes

In Regular Expressions, Character Classes (often called shorthand character classes) are special backslash \ notations used to match specific types of characters, like digits, letters, or whitespace.

They provide a fast and clean way to search for generic types of data without typing out every single letter or number.

Common Character Classes

Pro Tip: Notice the pattern? A lowercase letter matches the type (e.g., \d for digit), and the uppercase version does the exact opposite (\D for non-digit)!

1. Extracting Digits with \d

The \d class is incredibly useful for finding phone numbers, zip codes, or extracting numeric values from messy strings.

let text = "My phone number is 555-1234.";

// Find all digits in the string using \d and the 'g' flag
let result = text.match(/\d/g);
console.log(result); // ["5", "5", "5", "1", "2", "3", "4"]

2. Word Characters with \w

The \w class matches "word characters". It is important to remember that \w includes numbers and underscores (_), but not spaces or punctuation.

let text = "Hello World! 100%";

// Match all word characters
let words = text.match(/\w/g);
console.log(words.join("")); // HelloWorld100
// Match all NON-word characters
let nonWords = text.match(/\W/g);
console.log(nonWords); // [" ", "!", " ", "%"]

3. Handling Whitespace with \s

The \s class is perfect for splitting strings into arrays based on spaces, or for cleaning up extra spaces inside a document.

let text = "Is this    too much   space?";

// Let's replace every whitespace character with a hyphen
let clean = text.replace(/\s/g, "-");
console.log(clean); // "Is-this----too-much---space?"