The toUpperCase() method returns the calling string value converted to upper case.
str.toUpperCase()
A new string representing the calling string converted to upper case.
The toUpperCase() method returns the value of the string converted to upper case. toUpperCase() does not affect the value of the string itself.
toUpperCase()
console.log('alphabet'.toUpperCase()); // 'ALPHABET'
| Specification | Status | Comment |
|---|---|---|
| ECMAScript 1st Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.0. |
| ECMAScript 5.1 (ECMA-262) The definition of 'String.prototype.toUpperCase' in that specification. | Standard | |
| ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'String.prototype.toUpperCase' in that specification. | Standard | |
| ECMAScript Latest Draft (ECMA-262) The definition of 'String.prototype.toUpperCase' in that specification. | Living Standard |
| Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|---|
| Basic support | Yes | Yes | Yes | Yes | Yes | Yes |
| Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
|---|---|---|---|---|---|---|---|
| Basic support | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
String.prototype.toLocaleLowerCase()String.prototype.toLocaleUpperCase()String.prototype.toLowerCase()
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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toUpperCase