Count the occurrences of a character in a string

Count code points equal to a given character.

JavaScript Version 1.0.0 · MIT · .md

function countOccurrences({ text, char }) { return Array.from(text).filter(item => item === char).length; }

Input & expected output

{
  "text": "[email protected]",
  "char": "a"
}

3

The edge case

{
  "text": "😀 and 😀",
  "char": "😀"
}

2

Know the limits

• Iterates code points, so emoji count once.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Keep exploring

• Capitalize a string — Uppercase the first Unicode code point and preserve the remaining text.
• Reverse a string — Reverse Unicode code points without splitting surrogate pairs.
• Check a palindrome — Compare a string with its code-point reversal.