如果存在数据，如何在复选框上创建持久性功能

Question

I have seen many checkbox examples, but not this one.

I need a checkbox to remain checked if data is present in specific <input> fields. So it would need to be something that is constantly checking field status.

Basic checkbox:

<input class="checkbox" type="checkbox" unchecked onclick="shipping()"/>

It calls a function that removes a <div> and adds a shipping info page. There is a back button there that will remove shipping page and add orig. If they entered shipping data I want that checkbox to be checked. Now if they click it again, the data they entered on the shipping page would disappear. And process can be repeated.

This is a PHP page so I am comfortable using javascript, jQuery or PHP. Just looking for the most reliable way.

Answer 1

JavaScript is the way to go because PHP can't react to what's happening in the browser. I would register an onchange event handler to the input that drives the checkbox. When the input is altered (ie when the handler is triggered):

1. Read the value, and if it is empty then...
2. Enable the checkbox.
3. Else, disable the checkbox and set it as checked

This should prevent a user of the UI from unchecking the box while there is content in the input