https://www.listenandlearn.org/blog/wp-content/themes/ll-2016/js/fake-jquery.js

1
2function selectAll(selector, container = false) {
3    return Array.from(!container ? document.querySelectorAll(selector) : container.querySelectorAll(selector));
4}
5function jQuery() {
6    return {
7        on:function (callback) {
8
9        },
10        ready: function (callback) {
11            if(document.readyState !== 'complete'){
12                document.addEventListener('DOMContentLoaded', function(e){
13                    callback(e)
14                })
15            } else {
16                callback()
17            }
18        }
19    }
20}
21function $(selector) {
22    let elems = selectAll(selector)
23    return {
24        validate:function (opts) {
25            elems.forEach(function (elem) {
26                validate(elem, opts)
27            })
28        }
29    }
30}