Analyze the internal principles of writing jQuery to trigger events

In web development, jQuery's event binding plays a very important role. It can help developers perceive various input parameter changes on the page and achieve real-time interaction with the page. To implement event binding, we need to understand the internal principles. So, can jQuery trigger events? Next, let’s find out.

1. How jQuery binds events

In jQuery, we can bind events in many ways, as shown below.

1.1 Binding events through selectors

Binding events through selectors is one of the most commonly used methods in jQuery. The code is as follows:

$('#btn').click(function(){
  console.log('btn clicked');
});

The above code binds a click event through the selector. When the button with the id btn on the page is clicked, "btn clicked" will be output to the console.

1.2 Binding events through the .on() method

After jQuery version 1.7, it is officially recommended to use the .on() method to bind events. The code is as follows:

$('#btn').on('click', function(){
  console.log('btn clicked');
});

It is also the click event of the bound button, but it is implemented using the .on() method. This method is more commonly used in jQuery.

1.3 Bind events through the .bind() method

In older versions, you can also use the .bind() method to bind events. The code is as follows:

$('#btn').bind('click', function(){
  console.log('btn clicked');
});

2. How jQuery triggers events

After understanding how jQuery binds events, let’s next discuss how jQuery triggers events. Typically, we trigger events through user interaction, etc. However, in some cases, we also need to trigger the event we need after other events are triggered, which requires using jQuery to manually trigger the event.

2.1 Use the .trigger() method to trigger events

In jQuery, we can use the .trigger() method to manually trigger events. As shown below:

$('#btn').trigger('click');

The above code indicates that when the button with id btn on the page is clicked, the click event bound to the button is directly triggered.

2.2 Use the .triggerHandler() method to trigger events

Different from the .trigger() method, the .triggerHandler() method only triggers the event handler of the first matching element. The code is as follows:

$('#btn').triggerHandler('click');

3. Summary

Through the above explanation, we can understand that in jQuery, whether it is binding events or triggering events, it is very simple. We can bind various events through the selector, .on() method or .bind() method; manually trigger the required events through the .trigger() or .triggerHandler() method. Of course, we need to be careful to avoid abusing manual triggering events to prevent it from affecting program performance and readability.

The above is the detailed content of Analyze the internal principles of writing jQuery to trigger events. For more information, please follow other related articles on the PHP Chinese website!