JSFiddle - React, Tailwind, and code Playground

HTML

<div class="class0"> <a href="">link</a> </div>
	<div class="class0"></div>
	<div class="class0"></div>

JavaScript

var $ = function (selector){
			
			this.tags = document.querySelectorAll(selector);

			if (this.$) {					// возможно для вызова методов цепочки
			//if (!(this instanceof window)) {
				console.log("2", this.$);
				return new $(selector);
			}
			
		}
		
		$.prototype.addClass = function(className){
			for (var i = 0; i < this.tags.length; i++){
				this.tags[i].classList.add(className);
			}
			return this;
		}
		
		
		
		$.prototype.html = function(){
			var clone = new $('_');
			clone.tags = this.tags;
			clone.toString = function() {
				return this.tags[0].innerHTML;
			};
			return clone;
		}
		
		var result = $('div').html().addClass('class2').html();
		document.querySelectorAll('div')[2].innerHTML = result;