How to achieve the effect of pause time in javascript

JavaScript is a popular programming language often used to build dynamic web pages and interactive applications. In web development, controlling time is an important part because time affects aspects of page elements, animations, and user interaction. In JavaScript, we have many ways to control time, including timers, delayers, animation frames, etc. But sometimes, we need to pause time in order to perform some specific operations, such as waiting for an asynchronous task to complete or waiting for the user to make a selection. This article discusses how to stop time using JavaScript.

1. Timer

In JavaScript, we can use the setInterval() and setTimeout() functions to implement timers. The setInterval() function can call a specified function periodically, and the setTimeout() function can call a specified function after a certain period of time. But these two functions are not very useful when we want to pause time.

For example, if we want to pause for 2 seconds before executing subsequent code, we may need to write like this:

setTimeout(function() {
  // 暂停 2 秒钟
  setTimeout(function() {
    // 执行后续代码
  }, 2000);
}, 0);

But this method is not elegant and direct enough. Therefore, we can use Promise and async/await methods to achieve a more elegant and direct way.

2. Promise

Promise is an asynchronous programming model that can simplify complex asynchronous operations and handle the status and results of asynchronous operations in code.

By using Promise, we can easily handle timer issues. The following is an example code that uses Promise pause time:

function sleep(time) {
  return new Promise(resolve => setTimeout(resolve, time));
}

async function run() {
  console.log('开始执行代码');
  // 暂停 2 秒钟
  await sleep(2000);
  console.log('暂停时间结束，开始执行后续代码');
}

run();

In this example, we define a sleep() function, which returns a Promise object, and use the setTimeout() function to implement the pause time. In the run() function, we use the async/await method to wait for the return result of the sleep() function to achieve the effect of pause time.

3. Animation Framework

In addition to Promise and timers, we can also use animation frameworks to achieve the effect of pause time.

In JavaScript, there are a variety of animation frameworks to choose from, such as jQuery, Greensock and Anime.js. These frameworks can help us implement complex animation effects and provide a flexible API to control time.

For example, the code for using Greensock pause time is as follows:

// 创建一个 TimelineMax 实例
const timeline = new TimelineMax();

// 添加一个延时
timeline.addPause(2);

// 添加一些动画
timeline.to('#element', 1, { x: 100 })
       .to('#element', 1, { y: 100 })
       .to('#element', 1, { x: 0 })
       .to('#element', 1, { y: 0 });

// 开始播放动画
timeline.play();

In this example, we first create a TimelineMax instance and use the addPause() method to add a pause time. We then added some animation effects and called the play() method at the end to start the animation.

4. Summary

JavaScript provides a variety of ways to control time, including timers, Promise and animation frames. When we want to pause time, we can use Promise and async/await methods for an elegant and direct approach, or use animation frameworks for a more flexible approach. Which method to choose depends on the actual situation and personal preference.

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