Challenge 1
Find whether a string contains `cat`.
javascript
Your answer
const found = //.test(text);Press Ctrl⌘Enter to check your answer
Code Completion
9 Challenges
Complete the JavaScript Regular Expression Code
Practice patterns, captures, flags, match indices, Unicode properties, and global replacement.
Advanced
~8 min read
Challenge 2
Match one ASCII digit.
javascript
Your answer
const digit = //.test(text);Press Ctrl⌘Enter to check your answer
Challenge 3
Require the whole input to be `cat`.
javascript
Your answer
const exact = //.test(text);Press Ctrl⌘Enter to check your answer
Challenge 4
Capture the four-digit year from `2026-09`.
javascript
Your answer
const match = /(?<year>/.exec(text);Press Ctrl⌘Enter to check your answer
Challenge 5
Get every numeric substring.
javascript
Your answer
const values = text.match(/\d+/);Press Ctrl⌘Enter to check your answer
Challenge 6
Match one Unicode code point with dot.
javascript
Your answer
const one = /^.$/.test(text);Press Ctrl⌘Enter to check your answer
Challenge 7
Match one or more Unicode letters.
javascript
Your answer
const letters = /^\p{Letter}+$/.test(text);Press Ctrl⌘Enter to check your answer
Challenge 8
Replace every dash with a slash.
javascript
Your answer
const result = text.replace(/-//);Press Ctrl⌘Enter to check your answer
Challenge 9
Expose match start/end ranges for a RegExp result.
javascript
Your answer
const match = /\d+/.exec(text);Press Ctrl⌘Enter to check your answer