Joomla's built in form validation function USES methods

Here is how to use it:
Enter the following code at the top of the page where you want to use the form's functionality
JHTML: : _ (' behaviors. Formvalidation ');
Then add the following script to the page

 
<script type="text/javascript"> 
function formValidate(f) { 
if (document.formvalidator.isValid(f)) { 
f.check.value='<?php echo JUtility::getToken(); ?>';//send token 
return true; 
} 
else { 
alert('Some values are not acceptable. Please retry.'); 
} 
return false; 
} 
</script> 

Modify the code at the form location

<form ... onsubmit="return formValidate(this)"> 

After the above code has been added, validation will take effect as long as class="required" is added to the input in the form.
Joomla's validation scripts are implemented in class, and the name of the class determines which validation method is used.
The most common class="required" means required
Class ="validate-email" means validate the email address
Verification method can be used in combination. For example, I need Email to comply with the format before I can submit. I can write as follows:
Class = "validate - email required"

Customized verification method:
The Joomla validation feature supports customization, and you can set up validation rules that are not commonly used.
For example, I need to make a password item and a password item to confirm that the two input fields have the same value before I can submit. The following script can be added

 
document.formvalidator.setHandler('passverify', function (value) { return ($('password').value == value); }); 
<input type="password" value="" class="validate-passverify" />