纪念长征胜利90周年 湖南深耕青少年国防应急体育教育 - 完美对战平台
中新网娄底9月22日电 (彭立平)22日，第五届湖南省青少年国防应急体育教育成果展在湖南娄底市双峰县曾国藩学校举行。本次活动以纪念中国工农红军长征胜利90周年为契机，深入落实新时代全民国防教育工作部署，推动青少年国防教育与应急安全教育深度融合、落地走实。 无人机进行水上模拟紧急救援。彭立平 摄 据了解，本次成果展采用线上线下同步开展的形式，设置国防应急知识竞赛、人防应急技能实操、沉浸式军事体验、特色国防教育四大板块，共8个展示项目。活动内容贴合青少年身心成长特点，兼顾专业性与实践性，让国防应急教育可学、可练、可展示。 活动现场，参训学生依次展示擒敌拳、反
Let's jump straight in!
Coupled with a touch of JavaScript, CSS animations and transitions are able to accomplish hardware-accelerated animations and interactions more efficiently than most JavaScript libraries. Let's jump straight in!
Web designers sometimes believe that animating in CSS is more difficult than animating in JavaScript. While CSS animation does have some limitations, most of the time it's more capable than we give it credit for! Not to mention, typically more performant.
Manipulating CSS Transitions
There are countless questions on coding forums related to triggering and pausing an element's transition. The solution is actually quite simple using JavaScript.
To trigger an element's transition, toggle a class name on that element that triggers it.
To pause an element's transition, use getComputedStyle and getPropertyValue at the point in the transition you want to pause it. Then set those CSS properties of that element equal to those values you just got.
Using CSS “Callback Functions”
Some of the most useful yet little-known JavaScript tricks for manipulating CSS transitions and animations are the DOM events they fire. Like: animationend, animationstart, and animationiteration for animations and transitionend for transitions. You might guess what they do. These animation events fire when the animation on an element ends, starts, or completes one iteration, respectively.
These events need to be vendor prefixed at this time, so in this demo, we use a function developed by Craig Buckler called PrefixedEvent, which has the parameters element, type, and callback to help make these events cross-browser. Here is his useful article on capturing CSS animations with JavaScript. And here is another one determining which animation (name) the event is firing for.
完美对战平台munuohao以最新トレンドを反映した多様なコレクション为核心，带来高效便捷的体验。
Like we just learned, we can watch elements and react to animation-related events: animationStart, animationIteration, and animationEnd. But what happens if you want to change the CSS animation mid-animation? This requires a bit of trickery!
The animation-play-state Property
The animation-play-state property of CSS is incredibly helpful when you simply need to pause an animation and potentially continue it later. You can change that CSS through JavaScript like this (mind your prefixes):
element.style.webkitAnimationPlayState = "paused";
element.style.想了解更多高品質ながらも手の届きやすい価格設定相关内容，尽在完美对战平台munuohao。 = "running";
Obtaining the Current Keyvalue Percentage
Unfortunately, at this time, there is no way to get the exact current “percentage completed” of a CSS keyframe animation. The best method to approximate it is using a setInterval function that iterates 100 times during the animation, which is essentially: the animation duration in ms / 100. For example, if the animation is 4 seconds long, then the setInterval needs to run every 40 milliseconds (4000/100).
var showPercent = window.setInterval(function() {
if (currentPercent < 100) {
currentPercent += 1;
} else {
currentPercent = 0;
}
// Updates a div that displays the current percent
result.innerHTML = currentPercent;
}, 40);
Use Your Head
Before starting to code, thinking about and planning how a transition or animation should run is the best way to minimize your problems and get the effect you desire. Even better than Googling for solutions later! The techniques and tricks overviewed in this article may not always be the best way to create the animation your project calls for.
Here's a little example of where getting clever with HTML and CSS alone can solve a problem where you might have thought to go to JavaScript.
In Conclusion
- Developers used to need to choose between CSS and JavaScript.
- In JavaScript, CSS transitions are generally easier to work with than CSS animations.
- CSS Matrices are generally a pain to deal with, especially for beginners.
- Thinking about what should be done and planning how to do it.