jSpreadsheet plugin formula (formula bar + editor in cell) :

This plugin is a premium plugin available on Repo of JSpreadsheet plugins

Download full version of Formula Documentation

you can try this plugin in limited version in your jspreadsheet in localhost :

<script src="https://demo.gbonnaire.fr/dist/jexcel.formula.js"></script>
<link rel="stylesheet" href="https://demo.gbonnaire.fr/dist/jexcel.formula.css" type="text/css" />