JSFiddle - React, Tailwind, and code Playground

JavaScript

function createItem() {
    var item = bigSize();
    return item;
}

function bigSize() {
    var a = new Array(9999);
    for (var i = 0; i < a.length; i++) {
        a[i] = new Array(999);
    }
    return a;
}

var myGlobal;
window.setTimeout(function(){
    myGlobal = createItem();
    myGlobal = null;
},1000);