Get/Set content of a TinyMCE visual or text editor with JavaScript

wordpress-tinymce.js

/* 

Based on: http://wordpress.stackexchange.com/questions/42652/#answer-42729

These functions provide a simple way to interact with TinyMCE (wp_editor) visual editor.
This is the same thing that WordPress does, but a tad more intuitive.
Additionally, this works for any editor - not just the "content" editor.

Usage:

0) If you are not using the default visual editor, make your own in PHP with a defined editor ID:
  wp_editor( $content, 'tab-editor' );
  
1) Get contents of your editor in JavaScript:
  tmce_getContent( 'tab-editor' )
  
2) Set content of the editor:
  tmce_setContent( content, 'tab-editor' )

Note: If you just want to use the default editor, you can leave the ID blank:
  tmce_getContent()
  tmce_setContent( content )
  
Note: If using a custom textarea ID, different than the editor id, add an extra argument:
  tmce_getContent( 'visual-id', 'textarea-id' )
  tmce_getContent( content, 'visual-id', 'textarea-id')
  
Note: An additional function to provide "focus" to the displayed editor:
  tmce_focus( 'tab-editor' )

=========================================================
*/
function tmce_getContent(editor_id, textarea_id) {
  if ( typeof editor_id == 'undefined' ) editor_id = wpActiveEditor;
  if ( typeof textarea_id == 'undefined' ) textarea_id = editor_id;
  
  if ( jQuery('#wp-'+editor_id+'-wrap').hasClass('tmce-active') && tinyMCE.get(editor_id) ) {
    return tinyMCE.get(editor_id).getContent();
  }else{
    return jQuery('#'+textarea_id).val();
  }
}

function tmce_setContent(content, editor_id, textarea_id) {
  if ( typeof editor_id == 'undefined' ) editor_id = wpActiveEditor;
  if ( typeof textarea_id == 'undefined' ) textarea_id = editor_id;
  
  if ( jQuery('#wp-'+editor_id+'-wrap').hasClass('tmce-active') && tinyMCE.get(editor_id) ) {
    return tinyMCE.get(editor_id).setContent(content);
  }else{
    return jQuery('#'+textarea_id).val(content);
  }
}

function tmce_focus(editor_id, textarea_id) {
  if ( typeof editor_id == 'undefined' ) editor_id = wpActiveEditor;
  if ( typeof textarea_id == 'undefined' ) textarea_id = editor_id;
  
  if ( jQuery('#wp-'+editor_id+'-wrap').hasClass('tmce-active') && tinyMCE.get(editor_id) ) {
    return tinyMCE.get(editor_id).focus();
  }else{
    return jQuery('#'+textarea_id).focus();
  }
}

WHen you setContent, you might want to pull the current content from the textarea and append the new content, for example:

return jQuery('#'+textarea_id).val( jQuery('#'+textarea_id).val() + content );