String.prototype.toLowerCase()
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The toLowerCase() method of String values returns this string converted to lower case.
Try it
const sentence = "The quick brown fox jumps over the lazy dog.";
console.log(sentence.toLowerCase());
// Expected output: "the quick brown fox jumps over the lazy dog."
Syntax
js
toLowerCase()
Parameters
None.
Return value
A new string representing the calling string converted to lower case.
Description
The toLowerCase() method returns the value of the string converted to
lower case. toLowerCase() does not affect the value of the string
str itself.
Examples
Using toLowerCase()
js
console.log("ALPHABET".toLowerCase()); // 'alphabet'
Specifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-string.prototype.tolowercase |