萌新看JavaScript入门书籍return false 加载两次疑问
<!DOCTYPE html>
<html>
<head>
<title>Rotating Banner with Links </title>
<script src="script08.js"></script>
<link rel="stylesheet" href="script01.css">
</head>
<body>
<div class="centered">
<a href="linkPage.html"><img src= "images/banner1.gif" id="adBanner" alt="ad banner"></a>
</div>
</body>
</html>
window.onload = initBannerLink;
var thisAd = 0;
function initBannerLink() {
if (document.getElementById("adBanner").parentNode.tagName == "A") {
document.getElementById("adBanner").parentNode.onclick = newLocation;
}
rotate();
}
function newLocation() {
var adURL = new Array("negrino.com","sun.com","microsoft.com");
document.location.href = "http://www." + adURL[thisAd];
return false; //为什么不加return false 会加载url两次,两次分别是哪个语句造成的
}
function rotate() {
var adImages = new Array("images/ banner1.gif","images/banner2.gif","images/banner3.gif");
thisAd++;
if (thisAd == adImages.length) {
thisAd = 0;
}
document.getElementById("adBanner").src = adImages[thisAd];
setTimeout(rotate, 3 * 1000);
}