string.normalize

The normalize() method returns the Unicode Normalization Form of a given string (if the value isn't a string, it will be converted to one first).

Syntax

str.normalize([form])

Parameters

form

One of "NFC", "NFD", "NFKC", or "NFKD", specifying the Unicode Normalization Form. If omitted or undefined, "NFC" is used.

• NFC — Normalization Form Canonical Composition.
• NFD — Normalization Form Canonical Decomposition.
• NFKC — Normalization Form Compatibility Composition.
• NFKD — Normalization Form Compatibility Decomposition.

Return value

A string containing the Unicode Normalization Form of the given string.

Errors thrown

RangeError

A RangeError is thrown if form isn't one of the values specified above.

Description

The normalize() method returns the specified Unicode Normalization Form of the string. It does not affect the value of the string itself.

Examples

Using normalize()

// Initial string

// U+1E9B: LATIN SMALL LETTER LONG S WITH DOT ABOVE
// U+0323: COMBINING DOT BELOW
var str = '\u1E9B\u0323';


// Canonically-composed form (NFC)

// U+1E9B: LATIN SMALL LETTER LONG S WITH DOT ABOVE
// U+0323: COMBINING DOT BELOW
str.normalize('NFC'); // '\u1E9B\u0323'
str.normalize();      // same as above


// Canonically-decomposed form (NFD)

// U+017F: LATIN SMALL LETTER LONG S
// U+0323: COMBINING DOT BELOW
// U+0307: COMBINING DOT ABOVE
str.normalize('NFD'); // '\u017F\u0323\u0307'


// Compatibly-composed (NFKC)

// U+1E69: LATIN SMALL LETTER S WITH DOT BELOW AND DOT ABOVE
str.normalize('NFKC'); // '\u1E69'


// Compatibly-decomposed (NFKD)

// U+0073: LATIN SMALL LETTER S
// U+0323: COMBINING DOT BELOW
// U+0307: COMBINING DOT ABOVE
str.normalize('NFKD'); // '\u0073\u0323\u0307'

Specifications

Specification	Status	Comment
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'String.prototype.normalize' in that specification.	Standard	Initial definition.
ECMAScript 2017 Draft (ECMA-262) The definition of 'String.prototype.normalize' in that specification.	Draft

Browser compatibility

See also

• Unicode Standard Annex #15, Unicode Normalization Forms
• Unicode equivalence