Get_bloginfo(language) for javascript

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Javascript

PHP

WordPress

I only need to know how to make a javascript code in which, the code at first asks for WordPress website language.

What I have tried:

I know the code in PHP language if it helps:

mylocale = get_bloginfo('language');

P.S: I know that there is a javascript code which finds out about browser language.

<script type="text/javascript">
var userLang = navigator.language || navigator.userLanguage; 
alert ("The language is: " + userLang);
</script>

But I need to find out about wordpress langugae, e.g: lang="en-US"