Ajax+Servlet to implement refresh-free drop-down linkage (code attached)-JS Tutorial-php.cn

This time I will bring you Ajax+Servlet (with code) to implement non-refresh drop-down linkage.What are the precautions? The following is a practical case. Let’s take a look.

The drop-down linkage function can be said to be very commonly used, such as when selecting province, city and other information; or when selecting major categories or subcategories. In short, drop-down linkage is very commonly used. Today I will share with you a simple two-level drop-down linkage function.

Major category drop-down box: When the page is loaded, the drop-down options of the major categories are initialized, and the data is obtained from the database through the background code (of course, constant content such as provinces and cities can be given values directly), and then loaded into drop-down options.

Copy after login

Small category drop-down box: The small category drop-down option is to asynchronously submit the content of the selected major category to a Servlet through Ajax, then return the corresponding small category content, and finally load it into the small category drop-down option.

Copy after login

Obtain and load the JS code of the small category drop-down box:

Copy after login

I won’t go into details here on how to get data from the database. It’s just an ordinary query, which is relatively simple. Second-level linkage, third-level linkage, and multi-level linkage are all the same, that is, loading the contents of a drop-down box in advance, and then loading the subsequent drop-down box options based on the first selected content, and so on. Once you have mastered the second-level linkage, everything else becomes a matter of course, that is, just adding a few more drop-down boxes.

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!