jquery.js

function wrapJ(par) {
	let foundObj = null;

	if (!par) {
		return {
			isWrappedJ : true,
			length : function() { return 0; },
			get : function(i) { return this; },
			parent : function() { return this; },
			addClass : function (name) { return this; },
			removeClass : function (name) { return this; },
			outerWidth : function () { return 0; },
			outerHeight : function () { return 0; },
			width : function () { return 0; },
			height : function () { return 0; },
			css : function (name, value = null) { return this; },
			attr : function (name) { return this; },
			children : function () { return this; },
			each : function (fn) { return this; },
			ready : function (fn) { return this; },
			on : function (name, handler) { return this; },
			val : function (it = null) { return this; }
		};
	} else if (typeof par === "string") {
		let foundNodes = document.querySelectorAll(par);

		if (foundNodes.length == 0) {
			return {
				isWrappedJ : true,
				length : function() { return 0; },
				get : function(i) { return this; },
				parent : function() { return this; },
				addClass : function (name) { return this; },
				removeClass : function (name) { return this; },
				outerWidth : function () { return 0; },
				outerHeight : function () { return 0; },
				width : function () { return 0; },
				height : function () { return 0; },
				css : function (name, value = null) { return this; },
				attr : function (name) { return this; },
				children : function () { return this; },
				each : function (fn) { return this; },
				ready : function (fn) { return this; },
				on : function (name, handler) { return this; },
				val : function (it = null) { return this; }
			};
		} else {
			foundObj = foundNodes;
		}
	} else if ("isWrappedJ" in par) {
		return par;
	} else if (par === window) {
		foundObj = [window];
	} else if ("length" in par) {
		foundObj = [];
		for (let i = 0; i < par.length; i++) {
			foundObj.push(par[i]);
		}
	} else {
		foundObj = [par];
	}

	return {
		isWrappedJ : true,
		wrappedObj : foundObj,
		length : function() {
			return this.wrappedObj.length;
		},
		get : function(i) {
			return wrapJ(this.wrappedObj[i]);
		},
		parent : function() {
			return wrapJ(this.wrappedObj[0].parentNode);
		},
		addClass : function (name) {
			this.wrappedObj[0].classList.add(name);
			return this;
		},
		removeClass : function (name) {
			this.wrappedObj[0].classList.remove(name);
			return this;
		},
		outerWidth : function () {
			return this.wrappedObj[0].offsetWidth;
		},
		outerHeight : function () {
			return this.wrappedObj[0].offsetHeight;
		},
		width : function () {
			return this.wrappedObj[0].offsetWidth;
		},
		height : function () {
			return this.wrappedObj[0].offsetHeight;
		},
		css : function (name, value = null) {
			if (value) {
				this.wrappedObj[0].style[name] = value;
				return this;
			} else {
				return getComputedStyle(this.wrappedObj[0])[name];
			}
		},
		attr : function (name) {
			return this.wrappedObj[0].getAttribute(name);
		},
		children : function () {
			return wrapJ(this.wrappedObj[0].children);
		},
		each : function (fn) {
			this.wrappedObj.forEach((el, i) => {
				fn(wrapJ(el));
			});

			return this;
		},
		ready : function (fn) {
			if (document.attachEvent ? document.readyState === "complete" : document.readyState !== "loading"){
				fn();
			} else {
				document.addEventListener('DOMContentLoaded', fn);
			}

			return this;
		},
		on : function (name, second, third) {
			if (typeof second === "string") {
				this.wrappedObj[0].addEventListener(name, function(event) {
					let clickedElement = event.target;
					let matchingChild = clickedElement.closest(second);
					third(event, matchingChild);
				});
			} else {
				this.wrappedObj[0].addEventListener(name, second);
			}
			return this;
		},
		val : function (it = null) {
			if (it) {
				this.wrappedObj[0].value = it;
				return this;
			} else {
				return this.wrappedObj[0].value;
			}
		}
	};
}