JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://code.jquery.com/jquery-1.11.3.min.js"></script>

JavaScript

$(document).keypress(function(evt) {
    keyPressed = evt.keyCode ? evt.keyCode : evt.which;

    switch (keyPressed) {
        case 61:
        	alert("=");
        	break;
      	case 43:
        	alert("+")
        	break;
    }
});