Answer by Mohamed Mufeed for Updating an element after it has already been dynamically created in the DOM

The issue with your code is you set the id as symbol-price and you are querying for the element with idprice-price.

Note: you can access an object’s property directly; there is no need for looping if you know the property name.

Also if you are executing setInterval inside the main loop the stockId variable will be available automatically.

eg.

$(function() {    companies = [      {          name : 'Apple'        , symbol : 'AAPL'        , price : '577'        , shares : '1'      }    ]    for (var key in companies) {        var obj = companies[key];        var stockId = obj['symbol'] +'-price';        const prodEl = document.createElement('div');        prodEl.innerHTML = (        `<li class="stocks">  <div class='shares-price'><p id="${stockId}">Price: ${obj['price']}</p></div></li>        `        );        document.getElementById('stock-list').appendChild(prodEl);        document.getElementById(stockId).innerHTML = 200;    }   // set interval outside the main loop    setInterval(function() {        for (var key in companies) {            var obj = companies[key];            var stockId = obj['symbol'] +'-price';            document.getElementById(stockId).innerHTML = 200;        }    }, 1000)});