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js onmousewheel事件多次觸發問題解決方法
編輯:關於JavaScript     

我想做一個首屏和第二屏之間滾動鼠標滾輪就可以整平切換的效果,遇到了很多問題,後來在kk的幫助下,終於解決了這個問題,甚是歡喜,於是記錄一下:

我最初的代碼是這樣的:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<style>
div {
width: 700px;
height: 1000px;
}
.red {
background-color: red;
}
.yellow {
background-color: yellow;
}
</style>
</head>
<body>
<div class="red"> </div>
<div class="yellow"> </div>
<div class="red"> </div>
<div class="yellow"> </div>
<div class="red"> </div>
</body>

<script src="../jQuery/jquery.min.js"></script>
<script src="test.js"></script>
</html>
$(document).ready(function(){
var height = $(window).height(); //獲取浏覽器窗口當前可見區域的大小
    //鼠標滾動之後整屏切換
var scrollFunc = function(e){
var scrollTop = document.body.scrollTop || document.documentElement.scrollTop;
e = e || window.event;
if((e.wheelDelta<0|| e.detail>0) && scrollTop>=0 && scrollTop<height){ //不同浏覽器向下滾動 
$(document.body).animate({scrollTop:height}, "fast");
$(document.documentElement).animate({scrollTop:height}, "fast");
}else if((e.wheelDelta>0 || e.detail<0) && scrollTop>=height && scrollTop<=height+20){ //不同浏覽器向上滾動
$(document.body).animate({scrollTop:0}, "fast");
$(document.documentElement).animate({scrollTop:0}, "fast");
}
};
    //注冊事件
if(document.addEventListener){
document.addEventListener('DOMMouseScroll',scrollFunc,false);
}
window.onmousewheel = document.onmousewheel = scrollFunc; //IE、chrome、safira
});

這樣的代碼我在IE和火狐下測試都是正常的,但是在谷歌下onmousewheel事件總是會觸發多次,這是一個極其惱人的事情,為什麼會多次觸發呢?經過調試,我發現是我們每次滾動鼠標時都是很“凶殘”的一下子滾動很大一個幅度,而不是一小格一小格的慢慢滾動,這就導致了滾動的時候會多次觸發onmousewheel事件,調用scrollFunc函數,在函數內的animate函數沒有執行完的時候還是不斷的被調用,這樣就會出現滾動多次滾動條滾不下來頁滾不上去的情況。於是,我將上面的js代碼改成了下面這樣:

$(document).ready(function(){
var height = $(window).height();
var scrollFunc = function(e){
document.onmousewheel = undefined;
var scrollTop = document.body.scrollTop || document.documentElement.scrollTop;
e = e || window.event;
if((e.wheelDelta<0|| e.detail>0) && scrollTop>=0 && scrollTop<height){ 
$(document.body).animate({scrollTop:height}, "fast","linear",function(){
document.onmousewheel = scrollFunc;
});
$(document.documentElement).animate({scrollTop:height}, "fast","linear",function(){
document.onmousewheel = scrollFunc;
});
}else if((e.wheelDelta>0 || e.detail<0) && scrollTop>=height && scrollTop<=height+20){
$(document.body).animate({scrollTop:0}, "fast","linear",function(){
document.onmousewheel = scrollFunc;
});
$(document.documentElement).animate({scrollTop:0}, "fast","linear",function(){
document.onmousewheel = scrollFunc;
});
}
};
if(document.addEventListener){
document.addEventListener('DOMMouseScroll',scrollFunc,false);
}
document.onmousewheel = scrollFunc;
});

好了,現在的代碼已經能夠正常運行了,不過由於我是一只菜鳥,代碼寫的不夠精致,又被kk說了,在他的提示下,我將冗余的代碼又進行了一番修改:

$(document).ready(function(){
var height = $(window).height();
var width = $(window).width();
var body;
if(navigator.userAgent.indexOf("Firefox")>0 || navigator.userAgent.indexOf("MSIE")>0){
body = document.documentElement;
}else{
body = document.body;
}
var isFinish = true;
var scrollFunc = function(e){
if(isFinish){
var scrollTop = body.scrollTop;
e = e || window.event;
if((e.wheelDelta<0|| e.detail>0) && scrollTop>=0 && scrollTop<height-20){ 
scroll(height);
}else if((e.wheelDelta>0 || e.detail<0) && scrollTop>=height && scrollTop<=height+20){
scroll(0);
}
}

};
var scroll = function(height){
isFinish = false;
$(body).animate({scrollTop:height},"fast","linear",function(){
isFinish = true;
});
};
if(navigator.userAgent.indexOf("Firefox")>0){
if(document.addEventListener){
document.addEventListener('DOMMouseScroll',scrollFunc,false);
}
}else{
document.onmousewheel = scrollFunc;
}
});

終於得到簡介的代碼了,不得不說,通過解決這個問題,還是學到很多的。以後要向著“write less, do more”的目標更加努力了!!!

如果有哪裡寫的不對的,歡迎各位大神們指教,我會虛心學習的。

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