Short jQuery implementation on ES7+

simple-jquery.js

const $ = ::document.querySelectorAll;
{
    let p = Element.prototype;
    p.on = Element.prototype.addEventListener;
    p.find = function(s){ return this.querySelector(s) };
    p.html = function(s){
    	if(!s) return this.innerHTML;
        this.innerHTML = s;
        return this;
    };
    p = NodeList.prototype;
    p.on = function(e,f){
    	this.forEach($=>$.on(e,f));
        return this;
    };
    p.html = function(s) {
    	let a = Array.prototype;
        return a.reduce.call(
            a.map.call(this, $=>$.html(s)),
            (a, b) => a + b
        );
      	return this;
    };
}

// Usage

let alrt = function(){ alert(this.innerText) };

$('#btn0').on('click', alrt);

$('section > button').on('click', alrt);

$('section > div').html('<span>Set html text</span>');

$('pre')[0].html( $('div').html() );