How to draw Venn diagram & Chemistry Equation like the overleaf

[engineer-ece]

1. Need to draw venn diagram in Katex
2. Flow chart, design pattern
3. Chemistry equation.

please, teach how to render this kind of text in canvas from start to end. for future generation
5. https://www.overleaf.com/learn/latex/Chemistry_formulae

[ronkok]

This is a duplicate of issue #2232. KaTeX does not emulate the chemfig package, because it does not emulate the underlying TikZ package. (Issue #219).

I think KaTeX is the wrong tool for your task.