How to create a button in TinyMCE 4 that increments letter-spacing by 1px - tinymce-4

Question

I tried the same approach used in the answer to How to create a button in TinyMCE 4 that increments font size but this doesn't seem to work for letter-spacing. Does anyone have a way to make this work?
Thanks

Answer 1

Replace every font-size by letter-spacing and it will work:
http://fiddle.tinymce.com/Z9eaab/6
<script type="text/javascript">
tinymce.PluginManager.add('example', function(editor, url) {
// Add a button that opens a window
editor.addButton('example', {
text: 'Increment font size',
icon: false,
onclick: function() {
var currentFontSize = new Number($(tinyMCE.activeEditor.selection.getNode())
.css('letter-spacing').replace('px','')); // <-------- here
currentFontSize = currentFontSize + 1;
tinymce.activeEditor.formatter.register('mycustomformat', {
inline : 'span',
styles : {'letter-spacing' : currentFontSize + 'px'}
}); // ^-------- here
tinymce.activeEditor.formatter.apply('mycustomformat');
}
});
// Adds a menu item to the tools menu
editor.addMenuItem('example', {
text: 'Example plugin',
context: 'tools',
onclick: function() {
// Open window with a specific url
editor.windowManager.open({
title: 'TinyMCE site',
url: 'http://www.tinymce.com',
width: 400,
height: 300,
buttons: [{
text: 'Close',
onclick: 'close'
}]
});
}
});
});
tinymce.init({
selector: "textarea",
plugins: "example",
toolbar: "example undo redo | styleselect | bold italic | alignleft aligncenter alignright alignjustify | bullist numlist outdent indent | link image"
});
</script>
<form method="post" action="dump.php">
<textarea name="content"></textarea>
</form>