There's no point of enabling spell check for your html/js/css/c/php/py/etc files, but it can be very useful when you are writing in Markdown.
How to enable spell check only for only certain file extensions?
You can add a syntax specific setting:
Open a file with the syntax for which you want to enable spell-check (such as markdown in your case).
Open menu Settingsā¦
-> Settings - Syntax Specific
.
This file should contain a JSON object. Add the key/value pair: { "spell_check": true }
(or false for the reverse effect).
Save and close this file.