JSFiddle - React, Tailwind, and code Playground

HTML

<div id="foofoo" class="bar">Hello</div>
<div class="bar">World</div>

JavaScript

var foo = function( selector ) {
    
    this.print = function () {
        console.group("in print");
        console.log(this.elements[0].innerHTML);   
        console.groupEnd("in print");
        return this;
    }
    
    this.printAll = function () {
        console.group("in printAll");
        for (var i=0; i<this.elements.length; i++) {
             console.log(this.elements[i].innerHTML);
        }
        console.groupEnd("in printAll");
        return this;
    }
    
    this.elements = document.querySelectorAll( selector );
    return this;
  
}

console.group("id");
foo("#foofoo").print();
console.groupEnd("id");
console.group("class");
foo(".bar").printAll().print();
console.groupEnd("class");