'use strict'; document.addEventListener('DOMContentLoaded', function () { var $cells = getAll('.cell'); $cells.forEach(function (el) { var parentWidth = el.parentElement.offsetWidth; var percentage = el.offsetWidth / parentWidth * 100; el.innerHTML = '' + percentage.toFixed(2); // el.append(`${Math.round(el.offsetWidth)}`); }); // Functions function getAll(selector) { return Array.prototype.slice.call(document.querySelectorAll(selector), 0); } });