window.onload

Understanding the window.onload event

If you have ever worked with JavaScript, you might have come across the term window.onload at some point. It is one of the built-in events in JavaScript that is triggered when the entire web page and its resources have finished loading, including images, scripts, stylesheets, etc.

This means that if you want to run some code after everything on your web page has loaded, you can use the window.onload event to achieve this.

Example:

window.onload = function() {
  // your code here
}

In this example, we are assigning an anonymous function to the window.onload event. This function will be executed as soon as the entire web page has finished loading.

Another way to achieve the same result is by using the addEventListener() method.

Example:

window.addEventListener("load", function() {
  // your code here
});

In this example, we are adding an event listener to the window object, which listens for the load event and executes the provided function when it is triggered.

It is important to note that using window.onload will overwrite any previously assigned functions to this event. If you want to add multiple functions that should be executed when the page has loaded, you can use the addEventListener() method instead.

Example:

window.addEventListener("load", function() {
  // your first code block here
});

window.addEventListener("load", function() {
  // your second code block here
});

In this example, we are adding two event listeners to the window object, both listening for the load event and executing their respective functions when it is triggered.

By using the window.onload event or the addEventListener() method, you can ensure that your JavaScript code runs only after the entire web page has finished loading, which can prevent errors and ensure that your code executes as intended.