The toUpperCase()
method returns the calling string value converted to uppercase (the value will be converted to a string if it isn't one).
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Syntax
str.toUpperCase()
Return value
A new string representing the calling string converted to upper case.
Exceptions
TypeError
- When called on
null
orundefined
, for example,String.prototype.toUpperCase.call(undefined)
.
Description
The toUpperCase()
method returns the value of the string converted to uppercase. This method does not affect the value of the string itself since JavaScript strings are immutable.
Examples
Basic usage
console.log('alphabet'.toUpperCase()); // 'ALPHABET'
Conversion of non-string this
values to strings
This method will convert any non-string value to a string, when you set its this
to a value that is not a string:
const a = String.prototype.toUpperCase.call({ toString: function toString() { return 'abcdef'; } }); const b = String.prototype.toUpperCase.call(true); // prints out 'ABCDEF TRUE'. console.log(a, b);
Specifications
Specification |
---|
ECMAScript (ECMA-262) The definition of 'String.prototype.toUpperCase' in that specification. |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
toUpperCase | Chrome Full support 1 | Edge Full support 12 | Firefox Full support 1 | IE Full support 3 | Opera Full support 3 | Safari Full support 1 | WebView Android Full support 1 | Chrome Android Full support 18 | Firefox Android Full support 4 | Opera Android Full support 10.1 | Safari iOS Full support 1 | Samsung Internet Android Full support 1.0 | nodejs Full support 0.1.100 |
Legend
- Full support
- Full support