Form data is not persisted when validation is not met

[MaxwellGarceau]

Is your enhancement related to a problem? Please describe.

When filling out a form, if a user does not pass a validation check then the entire form will be lost. This is with JavaScript support enabled.

form-data-lost-on-validation-fail.mov

Designs

Non JavaScript solution - will work with or without JS

We can repopulate the <input> fields on failed submission with the submitted value from the $_POST variable in the mailchimp_form_field function.

JavaScript is enabled (optional)

• Option 1: We can store the in progress form data in local storage
• Option 2: We can validate form submissions on the FE to avoid clearing form data when it hits the BE

Describe alternatives you've considered

Considering that a user could become frustrated and leave without re-attempting form submission I think this is worth fixing.

Code of Conduct

• I agree to follow this project's Code of Conduct

[MaxwellGarceau]

Bug found

Found on #61

Update: The option to include JS support enqueues a script that is supposed to only clear the data on invalid form submission. That means existing functionality is not working as expected. However, the JS support option does not explicitly promise data persist on form submission so it's more of a "soft" bug.

wordpress/assets/js/mailchimp.js

Lines 15 to 23 in 0b93ec3

	// See if we're successful, if so, wipe the fields
	const reg = /class="|'mc_success_msg"|'/i;
	if (reg.test(data)) {
	$('#mc_signup_form').each(function () {
	this.reset();
	});
	$('#mc_submit_type').val('js');
	}