JSFiddle - React, Tailwind, and code Playground

HTML

<img src="2" id="faveToggle" class="faveIcon" onClick="toggleFave()">

JavaScript

if(document.getElementById('faveToggle').src.toString().indexOf("fave-false.png")>-1){
alert('1')   
 document.getElementById('faveToggle').src = "includes/icons/fave-true.png";
} else {
alert("2")
    document.getElementById('faveToggle').src = "includes/icons/fave-false.png";
}