Introduction
JavaScript Timed Events are a type of event that can trigger a function after a set amount of time has passed. We can use Timed Events to create things like animations, games, and other types of interactive applications. To create a Timed Event, you first need to create a function that JavaScript will execute after the set amount of time has passed. This function can be anything you want, but it is important to note that it will not be executed until the set amount of time has elapsed.
Use setTimeout() to create JavaScript timed events
Once you have created your function, you need to use the setTimeout() method to specify the time that should pass before the function is executed. The setTimeout() method takes two arguments: the first is the function that should be executed, and the second is the amount of time in milliseconds that should pass before the function is executed.
For example, let's say we want to create a Timed Event that will trigger a function after 5 seconds have passed. We would first create our function, and then we would use the setTimeout() method to specify that the function should be executed after 5 seconds have passed:
function myFunction() {
console.log("Wow");
}
setTimeout(myFunction, 5000); // 5000 milliseconds = 5 seconds
Output
Wow
Once you have created a Timed Event, it is important to note that it will not start running immediately. Instead, the Timed Event will start running when the JavaScript code that created it has finished running. This means that if you create a Timed Event inside a loop, it will not start running until the loop has finished.
It is also important to note that Timed Events are not guaranteed to run exactly at the time that they are scheduled for. This is because JavaScript is a single-threaded language, meaning that only one thing can happen simultaneously.
If there is a lot of other code running or the computer is busy with other tasks, the Timed Event may start running differently than scheduled. However, in most cases, Timed Events will start running close to the time that they are scheduled for.
If you need your Timed Event to run at a specific interval, you can use the setInterval() method, which we will discuss next.
Use setInterval() method to create JavaScript timed events
The setInterval() method is similar to setTimeout(), but it will execute the function repeatedly at the specified interval.
The setInterval() method takes two parameters: a function that will be executed at the specified interval and the time interval in milliseconds. For example, the following code will log "Hello, world!" to the console every 1000 milliseconds (1 second):
setInterval(function () {
console.log("Hello, world!");
}, 1000);
Output
Hello, world!
Hello, world!
Hello, world!
Hello, world!
Hello, world!
So, every 1 second, the anonymous function is executed, and the string “Hello, world!” is logged.
Both setTimeout() and setInterval() return a value that can be used to cancel the Timed Event. For example, the following code will cancel the Timed Event created by the previous code after 5000 milliseconds (5 seconds):
let interval = setInterval(function () {
console.log("Hello, world!");
}, 1000);
setTimeout(function () {
clearInterval(interval);
}, 5000);
Output
Hello, world!
Hello, world!
Hello, world!
Hello, world!
In the above code, we first create a Timed Event using setInterval(). This Timed Event will log "Hello, world!" to the console every 1000 milliseconds (1 second). We then create another Timed Event using setTimeout() that will clear the first Timed Event after 5000 milliseconds (5 seconds).
Summary
To create JavaScript Timed Events, we can make use of setTimeout and setInterval method.
It is important to note that Timed Events are not guaranteed to run at the scheduled time. In most cases, they will start running close to the time that they are scheduled for, but there are no guarantees. If you need your Timed Event to run at a specific time, you can use the setInterval() method.
References
setInterval() - Web APIs | MDN (mozilla.org)
setTimeout() - Web APIs | MDN (mozilla.org)
