What are the scenarios in which synchronous Ajax is used?

Here are some common scenarios where Ajax synchronously applied:

1. Form submission: When users have completed filling out the form, they can click the submit button to send the form data to the server for processing using Ajax synchronization, and then refresh the page synchronously or display the processing result after it is completed.
2. Data validation: when the user inputs data, you can use Ajax synchronization to send the data to the server for validation, and provide real-time feedback to the user about whether the input is legitimate.
3. User login: After entering their username and password on the login page, users can use Ajax to send the input data to the server for verification in real-time, and based on the validation result, determine whether to redirect to the login success page.
4. Data inquiry: When users perform search operations on the page, they can use Ajax synchronization to send the search criteria to the server for processing and display the search results synchronously.
5. Shopping cart update: When users add, delete, or modify the quantity of items in the shopping cart, they can use Ajax synchronous method to send the updated cart data to the server for processing, and synchronize the shopping cart information on the page.
6. Real-time communication: In scenarios such as chat rooms and instant messaging, users can use Ajax synchronous methods to send messages to the server for processing in real-time, and synchronously return the processing results to the users.

It should be noted that in certain specific cases, it may be necessary to use synchronous Ajax, such as when it is necessary to ensure the sequential execution of certain operations or to wait for the server to return results for further processing. However, in general, it is recommended to use asynchronous Ajax to improve user experience and page performance.