How find the missing glyph using javascript [like indesign preflight], and replace same glyph available font or

The situation:

I want to use basetext font, but some of the glyphs are missing in it, and are highlighted with pink boxes. common font [stix, etc.] have much more glyphs than basetext font. I can apply common font [stix, etc.]manually for each of the missing glyphs or insert two character and use kerning set it up, but it is tedious.

Question:

How find the missing glyph using javascript [like indesign preflight], and replace same glyph available font or insert two character and use kerning set it up?

Any one know how to do this?

Thanks in Advance,

~Jack