元素淡入，但不淡出

Element fading in, but not fading out

本文关键字：淡出 淡入 元素      更新时间：2023-09-26

我有以下javascript

function fadeIn(objectID, amount) {
object = document.getElementById(objectID + 'Des');
if(amount > 0)
{
    object.style.display ='block';
    object.style.opacity = '0';
}
var i = 0;
animatefadein = function()
{
    var MIN_OPACITY = 0;
    var MAX_OPACITY = 1;
    if ( (amount > 0 && object.style.opacity < MAX_OPACITY) || (amount < 0 && object.style.opacity > MIN_OPACITY)) 
    {
        var current = Number(object.style.opacity);
        var newopac = current + Number(amount);
        object.style.opacity = String(newopac);
        setTimeout('animatefadein()', 50);
    }
}
animatefadein();
if(amount < 0)
{
    object.style.display ='none';
}

}

我需要将显示设置为 none，因为如果用户浏览它们，则需要在其顶部放置另一个元素。

这是 HTML，

<div id='products'>
            <img src = './product1.png' usemap='#ourProducts' alt='Our Products' title='Hover over the names to find out more.'>
            <map id='ourProducts' name='ourProducts'>
                <area shape='rect' coords="55,55,210,110" href='#' id='forcePort' alt='ForcePort' title='ForcePort' onmouseover='fadeIn("forcePort",0.1)' onmouseout='fadeIn("forcePort",-0.1)'/>
                <area shape='rect' coords="105,248,270,290" href='#' id='quickPort' alt='QuickPort' title='QuickPort' onmouseover='fadeIn("quickPort",0.1)' onmouseout='fadeIn("quickPort",-0.1)'/>
                <area shape='rect' coords="390,260,535,303" href='#' id='scrinter' alt='Scrinter' title='Scrinter' onmouseover='fadeIn("scrinter",0.1)' onmouseout='fadeIn("scrinter",-0.1)'/>
                <area shape='rect' coords="675,242,835,292" href='#'  id='bugTrail' alt='Bug Trail' title='Bug Trail' onmouseover='fadeIn("bugTrail",0.1)' onmouseout='fadeIn("bugTrail",-0.1)'/>
                <area shape='rect' coords="688,42,858,138" href='#' id='dataExtract' alt='CRM Data Extractor' title='CRM Data Extractor' onmouseover='fadeIn("dataExtract",0.1)' onmouseout='fadeIn("dataExtract",-0.1)'/>
            </map>
            <div id='productDes'>
                <div id='scrinterDes'>
                                      Data that needs to be shown!
                </div>
                <div id='bugTrailDes'>
                </div>
                <div id='quickPortDes'>
                </div>
                <div id='forcePortDes'>
                </div>
                <div id='dataExtractDes'>
                </div>
            </div>
        </div>

如您所见，淡出不起作用。此外，如果您在 setTimeout 循环中放置一个计数器并将其打印到控制台，您将看到它在淡出事件上循环了无数次。这是有问题的网站，

网站

只需转到显示屏上的产品，然后将鼠标悬停在产品名称上即可。

我希望

你意识到这很容易用jQuery http://jquery.com/完成 脚本的问题在于Opacity和Display是两个不同的CSS属性，要做到这一点，你需要将Opacity设置为0，将Display: none更改为block或inline-block，然后对Opacity进行动画处理

在这里看到它：http://jsfiddle.net/V8SAx/

首先，你永远不应该这样称呼setTimeout：setTimeout('animatefadein()', 50)，因为它使用eval，这是非常缓慢和不安全的。

其次，这里有代码：

function fadeIn(objectID, amount,callback) {
    object = document.getElementById(objectID + 'Des');
    object.style.display ='block';
    object.style.opacity = String(Number(amount<0));
    animatefadein = function()
    {
        var MIN_OPACITY = 0;
        var MAX_OPACITY = 1;
        if ( (amount > 0 && object.style.opacity < MAX_OPACITY) ||
             (amount < 0 && object.style.opacity > MIN_OPACITY)
        ){
            var current = Number(object.style.opacity);
            var newopac = current + Number(amount);
            console.log(current + Number(amount));
            object.style.opacity = String(newopac);
            setTimeout(animatefadein, 50);
        }else{
            if(amount<0){object.style.display='none';}
            if(callback){callback();}
        }
    }
    animatefadein();
}
fadeIn('a',0.1,function(){fadeIn('a',-0.1);});

我添加了对回调的支持，该回调是在淡入淡出过程之后调用的，也许您会感兴趣。

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