Decode numeric HTML entities

Turn é and é style references into characters.

JavaScript Version 1.0.0 · MIT · .md

function decodeNumericEntities(text) { return text.replace(/&#(x[0-9a-f]+|\d+);/gi, (entity, code) => { const point = code[0].toLowerCase() === 'x' ? parseInt(code.slice(1), 16) : Number(code); return point <= 0x10ffff ? String.fromCodePoint(point) : entity; }); }

Input & expected output

"Café 😀"

"Café 😀"

The edge case

"�"

"�"

Know the limits

• Numeric references only; named ones such as é need an HTML parser. The original regex mishandled hexadecimal references.
• Out-of-range code points are left unchanged.

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.