loadstart
16 March, 2023
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About
The loadstart event is fired when the browser starts loading media data. This event is triggered at the beginning of the loading process, even before any data has been received from the server.
The loadstart event is typically used to indicate to the user that media content is about to be loaded, and it can be used to display a loading indicator or provide some other type of feedback to the user. The loadstart event can also be used to perform some initialisation or setup tasks that need to be performed before the media content is loaded.
For example, if you are using a custom video player on your website, you might want to initialise the player and load any necessary resources when the loadstart event is fired. This can help to improve the user experience by reducing the amount of time it takes for the video to start playing.
Event listener
Here's an example of how you can use the loadstart event:
HTML
<video id="my-video" src="my-video.mp4"></video>JavaScript
const myVideo = document.getElementById('my-video');
myVideo.addEventListener('loadstart', () => {
console.log('Media data is being loaded...');
});Here, we first get a reference to the video element using its id attribute. We then call the addEventListener method on the element to attach a loadstart event listener function. The function simply logs a message to the console when the loadstart event is fired.
This is just a basic example, but you can use the loadstart event in combination with other events and methods to create more complex media playback experiences, such as custom loading indicators or progress bars.
Property
You can attach the loadstart event to a media element using the onloadstart property:
const myVideo = document.getElementById('my-video');
myVideo.onloadstart = () => {
console.log('Media data is being loaded...');
};Here, we get a reference to the video element using its id attribute. We then assign a function to the onloadstart property of the element, which will be called when the loadstart event is fired. The function simply logs a message to the console when the loadstart event is fired.
Inline
Here's an example of using the onloadstart property inline:
<video id="my-video" src="my-video.mp4" onloadstart="console.log('Media data is being loaded...')"></video>Here, we include the onloadstart property as an attribute of the video element. The value of the attribute is a JavaScript code snippet that will be executed when the loadstart event is fired. In this case, we simply log a message to the console when the loadstart event is fired.
While this approach is easy to implement, it's generally not recommended to use inline event handlers as they can quickly clutter up your HTML code and make it harder to maintain. It's generally better to keep your JavaScript code separate from your HTML code, and attach event listeners programmatically using the addEventListener method.
Programmatic trigger
There is no loadstart() method that can be used to programmatically trigger the loadstart event on a media element. However, the dispatchEvent() method can be used to simulate a loadstart event:
const myVideo = document.getElementById('my-video');
// create a new loadstart event
const loadstartEvent = new Event('loadstart');
// dispatch the loadstart event on the media element
myVideo.dispatchEvent(loadstartEvent);Here, we create a new loadstart event using the Event constructor, and then dispatch that event on the myVideo element using the dispatchEvent() method.
Note that this approach is not recommended, and it's generally better to wait for the loadstart event to be fired by the browser in response to user actions or the loading of media data, and attach event listeners to handle those events as needed.
javascript
javascriptevent
loadevent
loadstart