String.prototype.toUpperCase()
 The toUpperCase() method returns the calling string value converted to uppercase (the value will be converted to a string if it isn't one). 
Try it
Syntax
toUpperCase()
Return value
A new string representing the calling string converted to upper case.Exceptions
 TypeError   When called on null or undefined, 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() {
    return 'abcdef';
  }
});

const b = String.prototype.toUpperCase.call(true);

// prints out 'ABCDEF TRUE'.
console.log(a, b);

Specifications

Specification
ECMAScript Language Specification # sec-string.prototype.touppercase

Browser compatibility




Desktop
Mobile
Server



Chrome
Edge
Firefox
Internet Explorer
Opera
Safari
WebView Android
Chrome Android
Firefox for Android
Opera Android
Safari on IOS
Samsung Internet
Deno
Node.js



toUpperCase
1
12
1
3
3
1
4.4
18
4
10.1
1
1.0
1.0
0.10.0


See also
 String.prototype.toLocaleLowerCase() String.prototype.toLocaleUpperCase() String.prototype.toLowerCase() 

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Last modified: Jul 28, 2022, by MDN contributors


    
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