JSFiddle - React, Tailwind, and code Playground

HTML

<div id="is"></div>

JavaScript

var s = new WeakMap (  );

s.set( document.getElementById("is"), "5" );

console.log( s.get( document.getElementById("is") ) );

 document.getElementById("is").remove();

setTimeout( function () {
console.log( s );
}, 5000 );