How to set locale in JavaScript, for example for t

问题:

I'd like to use the JavaScript toLocaleUpperCase() method to make sure that the capitalization works correctly for the Turkish language. I cannot be sure, however, that Turkish will be set as the user's locale.

Is there a way in modern browsers to set the locale in run time, if I know for sure that the string is in Turkish?

(I ran into this problem while thinking about Turkish, but actually it can be any other language.)

回答1:

There isn't really anything much out there but I came across this JavaScript setlocale function script that you might find useful.

回答2:

You unfortunately cannot set locale during runtime. All hope is not lost though, there are many good libraries on npm for you to use. Check out https://www.npmjs.com/package/upper-case and https://www.npmjs.com/package/lower-case for example, it will work for many other languages too.

If that's too much, you can roll your own simple library:

var ALL_LETTERS_LOWERCASE = 'abcçdefgğhıijklmnoöprsştuüvyz';
var ALL_LETTERS_UPPERCASE = 'ABCÇDEFGĞHIİJKLMNOÖPRSŞTUÜVYZ';

function toLowerCaseLetter(letter) {
  letter_index = ALL_LETTERS_UPPERCASE.indexOf(letter);
  return ALL_LETTERS_LOWERCASE[letter_index];
}
    
function toLowerCase(my_str) {
  var lower_cased = ''
  for (letter of my_str) {
      lower_cased += toLowerCaseLetter(letter);
  }
  return lower_cased;
}

console.log(toLowerCase('ÇDEFGĞHIİJKLMNOÖPRSŞTUÜ'))

Very similar for upper case version.

回答3:

This option may not have existed back in 2013 but may help new visitors on this topic:

According to MDN (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toLocaleUpperCase) the function toLocaleUpperCase takes an optional parameter 'locale'.

Setting the right language tag is a topic on its own (https://www.w3.org/International/articles/language-tags/). Simplest example looks like this

'selam dünya'.toLocaleUpperCase('tr'); // SELAM DÜNYA