JavaScript (ES2026) reference · String Methods

JavaScript String localeCompare() Method

Compare two strings using language rules; returns a negative number, 0 or a positive number. Use it to sort names.

JavaScript (ES2026) Since ES3

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Syntax

string.localeCompare(compareString, locales, options)

Parameter	Description
`compareString`	The string to compare with.
`locales` optional	A locale such as `"de"` or `"sv"`.
`options` optional	For example `{ sensitivity: "base" }` or `{ numeric: true }`.

Negative, zero or positive.

Sort like a human wouldTry it yourself

const names = ["Émile", "zoe", "Adam", "eve"];
console.log([...names].sort());
console.log([...names].sort((a, b) => a.localeCompare(b)));

Output

[ 'Adam', 'eve', 'zoe', 'Émile' ]
[ 'Adam', 'Émile', 'eve', 'zoe' ]

Numeric-aware sortingTry it yourself

const files = ["file10", "file2", "file1"];
console.log(files.sort((a, b) => a.localeCompare(b, undefined, { numeric: true })));

Output

[ 'file1', 'file2', 'file10' ]

Version	Change
JavaScript ES3	Added

string.toLowerCase() · Return the string converted to lowercase. Use it for case-insensitive comparisons.
array.sort() · Sort the array in place and return it. Without a compare function elements are sorted as strings, so numbers need one.
string.normalize() · Return the Unicode normalization form of a string so visually identical text compares equal (NFC, NFD, NFKC, NFKD).
JavaScript Strings · tutorial
JavaScript String Methods · tutorial