如何使用纯JavaScript制作fadeOut效果 [英] How to make fadeOut effect with pure JavaScript
本文介绍了如何使用纯JavaScript制作fadeOut效果的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在尝试使用 纯JavaScript 为 div
制作fadeOut效果。
I'm trying to make fadeOut effect for a div
with pure JavaScript.
这就是我目前使用的:
//Imagine I want to fadeOut an element with id = "target"
function fadeOutEffect()
{
var fadeTarget = document.getElementById("target");
var fadeEffect = setInterval(function() {
if (fadeTarget.style.opacity < 0.1)
{
clearInterval(fadeEffect);
}
else
{
fadeTarget.style.opacity -= 0.1;
}
}, 200);
}
div应该顺利淡出,但它会立即消失。
The div should fade-out smoothly, but it immediately disappear.
怎么了?我该如何解决?
What's wrong? How can I solve it?
推荐答案
最初当没有设置不透明度时,该值将为空字符串,这将导致算术失败。您可以将其默认为1并且它将起作用。
Initially when there's no opacity set, the value will be an empty string, which will cause your arithmetic to fail. You can default it to 1 and it will work.
function fadeOutEffect() {
var fadeTarget = document.getElementById("target");
var fadeEffect = setInterval(function () {
if (!fadeTarget.style.opacity) {
fadeTarget.style.opacity = 1;
}
if (fadeTarget.style.opacity > 0) {
fadeTarget.style.opacity -= 0.1;
} else {
clearInterval(fadeEffect);
}
}, 200);
}
document.getElementById("target").addEventListener('click', fadeOutEffect);
#target {
height: 100px;
background-color: red;
}
<div id="target">Click to fade</div>
在进行算术和比较时,空字符串似乎被JavaScript视为0(即使在CSS中它将空字符串视为完全不透明)
An empty string seems like it's treated as a 0 by JavaScript when doing arithmetic and comparisons (even though in CSS it treats that empty string as full opacity)
> '' < 0.1
> true
> '' > 0.1
> false
> '' - 0.1
> -0.1
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