inert-unert.js: a quick utility for applying or removing the inert property

inert-unert.js

// inert-unert.js: a quick utility for applying or removing the inert property 
// - @scottjehl, @filamentgroup
// (note: inert support polyfill is still needed in some browsers)
// usage:
//   when a modal element such as a dialog is active, 
//   this function will make unrelated elements inert, aiming to affect as few as possible
// example: inert( document.querySelector(".modal-open") ); 
function inert( allButThisElement ){
		function inertSiblings( node ){
			if( node.parentNode ){
				node.parentNode.childNodes.forEach(function(elem){
					if( elem !== node && elem.nodeType === 1 ){
						elem.inert = true;
					}
				});
				if( node.parentNode !== document.body ){
					inertSiblings(node.parentNode);
				}
			}
		}
		inertSiblings( allButThisElement );
}

// remove the inerts, when elements should be reachable again
// example: unert(); 
function unert(){
		document.querySelectorAll( "[inert]" ).forEach(function(elem){
			elem.inert = false;
		});
}