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).
Syntax
toUpperCase()
Return value
A new string representing the calling string converted to upper case.
Exceptions
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 Language Specification # sec-string.prototype.touppercase |
Browser compatibility
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