CKEditor upload image setup

CKEDITOR.replace( 'editor1', {
    filebrowserBrowseUrl: '/browser/browse.php',
    filebrowserUploadUrl: '/uploader/upload.php'
});

References :
File Manager Integration - CKEditor 4 Documentation 

CKEditor filebrowserUploadUrl php handler example

Notice the line

echo '';

References :
How to Add and Upload an Image using CKEditor - Paul Freeman-Powell

CKEditor dynamic set textarea value

CKEDITOR.instances.editor1.setData( 'This is the editor data.
' );

References :

CKEDITOR.editor - CKEditor 3 JavaScript API Documentation

CKEditor 4.0 change textarea size

CKEDITOR.replace('content', {height: 500});

References :

javascript - How to change the editor size of CKEditor? - Stack Overflow

Flask file upload

Example:
https://gist.github.com/dAnjou/2874714#file-server-py-L7