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.
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."
toLowerCase()
None.
A new string representing the calling string converted to lower case.
The toLowerCase() method returns the value of the string converted to lower case. toLowerCase() does not affect the value of the string str itself.
toLowerCase()
console.log("ALPHABET".toLowerCase()); // 'alphabet'
| Desktop | Mobile | Server | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Opera | Safari | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | WebView Android | WebView on iOS | Bun | Deno | Node.js | |
toLowerCase |
1 | 12 | 1 | 3 | 1 | 18 | 4 | 10.1 | 1 | 1.0 | 4.4 | 1 | 1.0.0 | 1.0 | 0.10.0 |
© 2005–2025 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toLowerCase