packdragon

Turns out the above solution doesn’t actually work. Neither using “prop” nor click() actually activate it and cause the categories to be entered with the submission. It’s just a cosmetic checkmark. I have instead resigned myself to just adding instructions using the following:

//Add instructions to STC subscription.
(function($) {
	$(document).ready(function() {
		$('.stc-categories').prepend('<div class="stc-instructions">*IMPORTANT: Select which categories you want to subscribe to below:</div>'); 
	})
})(jQuery);

I was looking for this solution as well. If a subscriber just enters an email address and hits submit, they subscribe to nothing. Possible solutions:

1. Make a category selection a required field.
2. If no categories are selected upon submission, select all by default.

In the meantime, I used jQuery to make that checkbox checked by default. I can foresee this might cause confusion if a user who is already subscribed wants to alter their selections, but nothing they can’t fix by clicking the appropriate boxes. I get a lot more empty subscriptions than I do users altering their selections.

For those who want to use my hackish solution…
1. Follow the instructions on this page for setting up a custom script file in your theme: https://stackoverflow.com/questions/11159860/how-do-i-add-a-simple-jquery-script-to-wordpress
2. In your script file, paste the following:

//Select All Categories by default so subscriber doesn't have an empty subscription
(function($) {
	$(document).ready(function() {
		$('.stc-checkbox input').prop('checked', true);
	})
})(jQuery);