使用Google闭包，通过类和id选择器获取DOM元素

Posted 2021-02-24

The Google Closure lets you get DOM elements with getElement( id ) and getElementByClass( class ). This function combines the two to let you get elements similarly to the way jQuery does. E.g. getElement( '#home .sidebar #links') returns the element with an id of 'links', within the element of class 'sidebar', within the element of id 'home'.

function getElement( selector ) {
	var split = selector.split(" ");
	var el = document;
	var len = split.length;
	var type, name;
	for( var i = 0; i < len; i++ ) {
		try {
			name = split[ i ];
			type = name[ 0 ];
			name = name.substr( 1, name.length - 1 );
			switch( type ) {
				case "#":
					el = goog.dom.getElement( name, el );
					break;
				case ".":
					el = goog.dom.getElementByClass( name, el );
					break;
				default:
					el = null;
			}
		} catch( e ) {	
			el = null;
			throw( "Error with getElement using selector: " + selector + ", error: " + e );
		}
	}
	if ( el == document ) el = null;
	return el;
}