stackFIDDLE

Install the Bookmarklet

1. First, make sure your browser's bookmark toolbar is visible.
2. Then, just drag the button to your bookmarks toolbar.

StackFiddle

Install the Chrome Extension

1. Go to the Chrome Store
2. Install the StackFiddle extension

Add to Chrome

Using StackFiddle

1. stackOverflow: Choose code blocks from a question
2. jsFIDDLE: Modify code blocks in jsFiddle