Wanna test UI on your page when changing your text?
Wanna edit some text directly in the browser itself?
designMode you can use your browser as a text editor.
Go to console and type:
document.designMode = 'on'
to turn it on. Valid values are
'off', default is
'off' in almost browsers.
You can now edit almost anything and everything in the DOM.
Originally posted on my blog here