The toLocaleUpperCase() converts the string into uppercase as toUpperCase method but based on locale settings on the browser.
Syntax
String.toLocaleUpperCase()
Example
var s1 = 'hello';
var s2 = 'Hello';
var s3 = 'hElLo';
document.write(s1.toLocaleUpperCase());
document.write(s2.toLocaleUpperCase());
document.write(s3.toLocaleUpperCase());