Suppose the user needs to fill in the name, address, date of birth, etc. In an HTML form. Then, before submitting the form to the server for further processing, the JavaScript program will check the form to ensure that the user has indeed entered the information and that the information meets the requirements.

What is a regular expression?

Regular expressions are objects that describe character patterns. The RegExp class of ECMAScript represents regular expressions, and both String and RegExp use regular expressions to define powerful functions of pattern matching, text retrieval and replacement.

Regular expressions are mainly used to verify the input data of the client. After the user fills in the form and clicks the button, the form will be sent to the server, where it is usually further processed by server scripts such as PHP and ASP.NET. Because of client authentication, Kunming IT training/thinking can save a lot of server-side system resources and provide a better user experience.