62 lines
1.2 KiB
Markdown
62 lines
1.2 KiB
Markdown
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---
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title: How to Create a Countdown Timer
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localeTitle: 如何创建倒数计时器
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---
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## 如何创建倒数计时器
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### 创建
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首先构建countdownTimer函数。
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```javascript
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function startCountdown(seconds){
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var counter = seconds;
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var interval = setInterval(() => {
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console.log(counter);
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counter--;
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if(counter < 0 ){
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// The code here will run when
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// the timer has reached zero.
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clearInterval(interval);
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console.log('Ding!');
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};
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}, 1000);
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};
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```
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### 执行
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现在，为了启动计时器，我们提供了`startCountdown()`其中一个数值作为参数，表示倒计时的秒数。
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```javascript
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startCountdown(10);
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// Console Output //
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// 10
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// 9
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// 8
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// 7
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// 6
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// 5
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// 4
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// 3
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// 2
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// 1
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// 0
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// Ding!
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```
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### 实例
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[Codepen - 倒数计时器](https://codepen.io/rdev-rocks/pen/jLogxY?editors=0012)
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### 更多资源
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使用的方法：
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* [的setInterval（）](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/setInterval)
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* [clearInterval（）](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/clearInterval)
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