This is how to extend Host(DOM,BOM) objects. But best to not do it at all, use wrappers.

.js

const $ = function(selector) { return document.querySelector(selector); }; // Returns first matched element or null
const $$ = function(selector) { return document.querySelectorAll(selector); }; // Returns NodeList of matched elements or empty NodeList []

// If you want to extend HTML DOM prototype do it this way or something like this.
// Check for property or method pre-existance. Obv if JS Engine already provides property or method, you don't want to override it with your own custom one.
// This works in IE9+ or can be done even in IE8+ 

// Adding a new method to all HTML elements via the HTMLElement prototype
if(!HTMLElement.prototype.remove) {
	// defineProperty because of enumeration
	Object.defineProperty(HTMLElement.prototype, 'remove', {
		value: function() {
			if (this.parentNode) {
				this.parentNode.removeChild(this);
			}
			return this; // Allow chaining 
		},	
	});
}