How javascript to get the OS system language in Chrome, not the browser language setting. I mean if your check "navigator.language" in debugger, what it shows is the browser language. However, it you change the language in the control pannel-->Clock,Language,and Region -->Region and Language-->Format , to, for example Romansh(Switzerland), the "navigator.language" will not reflect it.
By the way, if you check the "navigator.language" in IE11, it will show "rm-CH" in above example.
Thank you in advance for your clue.