How to remove old tinymce style_format classes when changing / updating format

Question

I have created some custom style formats, that add a class to a block level element. The problem is that when I apply one style it keeps the old class and adds the new class.

How do I remove the old class when switching to another format?

mce_options_article = {
        // ...
        formats: {
          p_grey: { selector: 'p', classes: 'grey' },
          p_red: { selector: 'p', classes: 'red' } 
        },
        style_formats: [
          {title: 'Paragraph Color', items: [
            {title: 'Grey ', format:'p_grey'},
            {title: 'Red ', format:'p_red'},
           ]},
        ]
        // ...
    }

Answer 1

Use attributes instead of classes.

This is what I did:

mce_options_article = {
    // ...
    formats: {
      p_grey: { selector: 'p', attributes: {'class':'grey'} }, // use attributes
      p_red: { selector: 'p', attributes: {'class':'red'} } // use attributes
    },
    style_formats: [
      {title: 'Paragraph Color', items: [
        {title: 'Grey ', format:'p_grey'},
        {title: 'Red ', format:'p_red'},
       ]},
    ]
    // ...
}