Is there a way to control an array of characters of languages different from English in javascript?

If I use var words=['ac', 'bd', 'bf','uy','ca'];, the system works.

But if I use var words=['cá', 'cả', 'biểu','bíu','tịu']; (Vietnamese characters), the system doesn’t work

Is there a way to control an array of characters of languages different from English in javascript?