JSFiddle - React, Tailwind, and code Playground
HTML
<span id='a' data-a='Hey There!'></span>
<span id='a1' data-a='Hey There!'></span>
<span id='b' data-b='Hey There!'></span>
JavaScript
var a = document.getElementById('a').getAttribute('data-a')
var a1 = document.getElementById('a1').getAttribute('data-a')
var b = document.getElementById('b').getAttribute('data-b')
console.log(a,b,a==b)
console.log(a,a1,a==a1)