JavaScript Timer Explained: setTimeout & setInterval

JavaScript timers are a mechanism used to execute specific code or functions after a specified time interval. They can execute once after a period of time or repeatedly. Timers can help achieve functions such as delayed loading, animation effects, and timed data updates.

JavaScript offers two types of timers: setTimeout() and setInterval().

1. setTimeout() is used to execute a specified code or function after a specified time interval. It takes two parameters: the code or function to execute, and the delay time in milliseconds.
2. setInterval() is used to repeatedly execute specified code or function at specified time intervals. It also takes two parameters: the code or function to be executed, and the time interval in milliseconds.

You can stop the timer from running by cancelling it (using clearTimeout() and clearInterval()).

Here is an example of using setTimeout() and setInterval().

// setTimeout示例
setTimeout(function() {
  console.log("Hello, World!");
}, 2000); // 2秒后输出"Hello, World!"

// setInterval示例（每隔1秒输出一次）
var count = 0;
var intervalId = setInterval(function() {
  console.log(count);
  count++;
  if (count > 5) {
    clearInterval(intervalId); // 停止计时器的执行
  }
}, 1000);

Timers are widely used in web development and can be used to implement many interesting and practical features.