JSFiddle - React, Tailwind, and code Playground

JavaScript

function callback () { console.log('all done'); }
    function asyncFunction(item) {
      console.log("in async function, item is " + item)
    }
    var itemsProcessed = 0;
    
    [1, 2, 3].forEach((item, index, array) => {
      asyncFunction(item, () => {
        itemsProcessed++;
        console.log("in callback area, itemsProcessed is " + itemsProcessed )
        if(itemsProcessed === array.length) {
          callback();
        }
      });
    });