// JavaScript Document



/* ------------------------------------------------------

	* 名前: rollover.js

	* 説明: 画像ファイルにマウスが触れた際に、画像の差し替えを行う

	* バージョン: 1.0

	* 最終更新日: 2008.10.16

	* 制作者: Hiroaki Nakagawa

	* Thanks: Daniel Nolan( http://www.dnolan.com/code/js/rollover/ )

------------------------------------------------------ */





// Rollover

// ------------------------------------------------------



	var elementTagName = "img";



	// 

	var clsName = "rollover";



	// 

	var postfixName = "_on";



	function rollOver() {

		// 

		var preloadImg = new Array();

		var elementImg

		var objectId = document.getElementsByTagName( elementTagName );



		for( i=0; i<objectId.length; i++ ) {



			if( objectId[i].className == clsName ) {



				// preload

				var imgSource = objectId[i].getAttribute( "src" );

				var fileType = imgSource.substring( imgSource.lastIndexOf( "." ), imgSource.length );

				var mouseoverImg = imgSource.replace( fileType, postfixName + fileType );



				objectId[i].setAttribute( "mouseoverImg" , mouseoverImg );



				// 

				preloadImg[i] = new Image();

				preloadImg[i].src = mouseoverImg;



				objectId[i].onmouseover = function() {

					elementImg = this.getAttribute( "src" );

					this.setAttribute( "src", this.getAttribute( "mouseoverImg" ));

				}



				objectId[i].onmouseout = function() {

					if ( !elementImg ) {

						elementImg = this.getAttribute( "src" ).replace( postfixName + fileType, fileType);

					} else {

						this.setAttribute( "src", elementImg );

					}

				}



			}

		}



	}



	function loadFunction( objctName, eventType, functionName ) {

		eval( objctName + "." + eventType + " = " + functionName );

	}



	// Program Execution

	loadFunction( "window", "onload", "rollOver" );



// ------------------------------------------------------