How to use init method of TinyMce in confluence?

I want to use ‘init’ function of the TinyMCE in confluence. But it needs an attribute named ‘selector’. What is the value of this selector in confluence?

          selector: 'body',
          setup: function(editor) {
            editor.on('init', function(e) {
              console.log('The Editor has initialized.');

Or maybe there is some other function overridden by confluence?