matchesSelector.js

1-matchesSelector.js

function matchesSelector(el, selector) {
	var p = Element.prototype;
	var f = p.matches || p.webkitMatchesSelector || p.mozMatchesSelector || p.msMatchesSelector || function(s) {
		return [].indexOf.call(document.querySelectorAll(s), this) !== -1;
	};
	return f.call(el, selector);
}

// Usage
matchesSelector(document.getElementById('myDiv'), 'div.someSelector[some-attribute=true]')

2-matchesSelector2.js

function matchesSelector(el, selector) {
	var p = Element.prototype;
	var f = p.matches || p.webkitMatchesSelector || p.mozMatchesSelector || p.msMatchesSelector || function(s) {
		return [].indexOf.call(this.parentNode.querySelectorAll(s), this) !== -1;
	};
	return f.call(el, selector);
}

Description.md

Often times we validate input before moving forward; ensuring a truthy value, ensuring forms data is valid, etc. But how often do we ensure an element qualifies for moving forward?
You can use a matchesSelector function to validate if an element is of a given selector match.

http://davidwalsh.name/essential-javascript-functions