How to find out which language subsets are drawn in a font and to what extent?

Question

Fonts

For example the font Roboto gfonts says? what is the trace. subsets :

• Cyrillic Extended (Supported by Roboto)
  
• Vietnamese (Supported by Roboto)
  
• Greek Extended (Supported by Roboto)
  
• Cyrillic (Supported by Roboto)
  
• Latin Extended (Supported by Roboto)
  
• Greek (Supported by Roboto)
  
• Latin (Supported by all Fonts)
  

How to find out for any font?

Answer 1

Open in the editor and see what characters are there?

Answer 2

I usually google the official site of the author of the font and look for specs there

Answer 3

let WINDOW_W;
$(window).on('resize', function(){
  WINDOW_W = $(window).outerWidth();
}).trigger('resize');