How jQuery avoids page refresh for AJAX requests

In recent years, with the advent of the Web 2.0 era, front-end technology has become more and more developed. jQuery, as a popular, efficient and streamlined JavaScript library, provides us with a lot of convenience in developing Web applications. Among them, jQuery's AJAX technology provides us with a method to implement asynchronous requests, which improves user experience and avoids the problem of page refresh.

However, AJAX also has some problems. Many developers have encountered such a problem when using AJAX: every time an AJAX request is sent, the current page will be refreshed, giving users a bad experience. So, how to avoid page refresh due to AJAX request? Here are some ways to disable refresh in jQuery AJAX.

1. Use the event.preventDefault() method

In the above question, we mentioned that the current page will be refreshed every time an AJAX request is sent. This is because the browser defaults caused by the behavior. Therefore, we can use the event.preventDefault() method to prevent the browser's default behavior. This method accepts an event object, which prevents the browser's default behavior for specific events.

The following is a sample code using the event.preventDefault() method:

$('#submit-button').click(function(event) {
  event.preventDefault();
  $.ajax({
    url: 'example.com',
    type: 'POST',
    data: {'name': 'John', 'age': 30},
    success: function(response) {
      alert(response);
    }
  });
});

Here, we pass the event object as a parameter to the callback function of the click event, and in The event.preventDefault() method is used in the function to prevent the browser's default form submission behavior. This will avoid page refresh problems.

2. Use the return false statement

In addition to using the event.preventDefault() method, we can also use the return false statement. This statement prevents the browser's default action on a specific event and prevents other statements in the code from being executed.

Look at the sample code below:

$('#submit-button').click(function() {
  $.ajax({
    url: 'example.com',
    type: 'POST',
    data: {'name': 'John', 'age': 30},
    success: function(response) {
      alert(response);
    }
  });
  return false;
});

Here, we use the return false statement to prevent the browser's default form submission behavior and avoid the execution of other statements in the code. This can also prevent page refresh issues.

It should be noted that if you use the return false statement in the callback function to prevent the browser's default operation, you need to add event.stopPropagation() after the statement, otherwise unnecessary problems may occur.

3. Use promise objects

Using promise objects can make the code more concise and easy to understand, and avoid problems caused by nested callback functions.

The following is a sample code using a promise object:

$('#submit-button').click(function() {
  var request = $.ajax({
    url: 'example.com',
    type: 'POST',
    data: {'name': 'John', 'age': 30}
  });
  request.then(function(response) {
    alert(response);
  });
  return false;
});

Here, we assign the request to a variable request and set the success callback function in the promise object. This can effectively avoid page refresh problems.

Although AJAX can effectively improve the user experience of the website, it also has some problems, such as page refresh. When using jQuery AJAX to disable refresh, we need to pay attention to the following points:

1. You need to use the event.preventDefault() method or the return false statement to prevent the browser's default operation.
2. The use of promise objects can make the code more concise and easy to understand, and avoid problems caused by nested callback functions.
3. If you use the return false statement to prevent the browser's default operation, you need to add event.stopPropagation() after the statement, otherwise unnecessary problems may occur.

In general, when using jQuery AJAX, it is very important to avoid page refresh, which can effectively improve the user experience, and the above methods can also solve this problem well. We just need to choose a method that suits us based on specific business needs.

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