在提交表单之前，如何检查HTML中的表单元素？

Question

I'm using PHP to validate and run my form, however, I want to check elements as they are filled out. How do I check an element for its current value prior to the submission of the form?

Answer 1

You need to use Javascript to validate the data in the form without sending it to the server.

http://www.elated.com/articles/form-validation-with-javascript/ may be useful

Answer 2

Documents have a forms collection, forms have an elements collection, elements that are form controls have associated DOM properties such as value , checked , selected and so specified in their related interfaces (eg HTMLInputElement , HTMLSelectElement ) that can be compared to allowed values and ranges.

There are many, many questions and articles on the subject. Search for form validation, have a go, ask questions.

Answer 3

You have two choices: either validat it with javascript before the form is submitted, or you check by PHP on the page it has been submitted to. usually it is wise to do both, in case javascript is turned off.