Character classes

A literal like /cat/ matches one exact sequence. A character class matches any one character from a set instead. \d means "any digit" - 0-9 - and it stands for exactly one character, not a whole number; to match "2026" you'd need four of them in a row (more on that next lesson).

You can also build your own class with square brackets: [aeiou] means "any one of these vowels," and matches the first one it finds anywhere in the string.

Your task: write hasDigit(str), true if str contains any digit (\d), and hasVowel(str), true if str contains any vowel ([aeiou]).

You'll practice:

Matching any digit with \d
Matching a custom set of characters with [...]

{
  "language": "js",
  "starterCode": "// Write hasDigit(str): true if str contains any digit.\nfunction hasDigit(str) {\n\n}\n\n// Write hasVowel(str): true if str contains any of a, e, i, o, u.\nfunction hasVowel(str) {\n\n}",
  "solution": "function hasDigit(str) {\n  return /\\d/.test(str);\n}\n\nfunction hasVowel(str) {\n  return /[aeiou]/.test(str);\n}",
  "hints": ["\\d inside a regex matches any single digit 0-9.", "[aeiou] matches any one of those characters, wherever it appears.", "Both are just .test() calls, same as the last lesson."],
  "tests": [
    { "name": "hasDigit finds a digit in a word", "code": "if (hasDigit('room7') !== true) throw new Error('hasDigit(\"room7\") should be true');" },
    { "name": "hasDigit is false with no digits", "code": "if (hasDigit('no numbers here') !== false) throw new Error('hasDigit(\"no numbers here\") should be false');" },
    { "name": "hasVowel finds a vowel", "code": "if (hasVowel('cat') !== true) throw new Error('hasVowel(\"cat\") should be true (the a)');" },
    { "name": "hasVowel is false with no vowels", "code": "if (hasVowel('rhythm') !== false) throw new Error('hasVowel(\"rhythm\") should be false');" }
  ]
}