Customizer: Add keyup events to sync textarea values.

[koopersmith]

We automatically sync text inputs with their js objects using keyup, but were not syncing for textarea. We should be doing both.

Since we don't have any controls in core with textareas, here's an easy way to test the patch.

1. Navigate to yoursite.com/wp-admin/customize.php
2. Open up your browser's JS console.
3. Drop this code block in the console:

   var textarea = jQuery('<textarea>').appendTo('#customize-theme-controls');
   var element = new wp.customize.Element( textarea );
   element.bind( function() {
   	console.log('element changed', arguments);
   });
   

4. Click inside the new textarea in the sidebar and type some text.
5. Click somewhere outside of the textarea.

With the patch, you should see the value changing in the console as you type. Without the patch, you'll only see a change when you click out of the textarea (triggering a change event).

Looks good.

Typing "Enter" in the textarea is disabled (no new line) as Enter/Return is globally caught by $('#customize-controls').on( 'keydown',... L:575 in customize-controls.dev.js.

Good catch, Andrew. This patch should allow enter to be pressed in textareas.

2.diff works well.

In [21024]:

Customizer: Add keyup events to sync textarea values. Props koopersmith. fixes #20879