Prohibition of Cyrillic input - it works on the computer, but not on the phone in WebView, how so?

Question

JavaScript

Made input validation with Cyrillic prohibition. In the browser it works - fine, in the webView - it doesn't work.

document.getElementById("name").onkeypress= function(event){
  var ew = event.which;
    if(ew < 49)
        return true;
  if(65 <= ew && ew <= 90)
        return true;
    if(97 <= ew && ew <= 122)
        return true;
  if(ew == 32)
    return true;
    return false;
    };

It seems nothing supernatural, but it does not work in webView. Javascript in webView is enabled. Why can this be so?