Abstract: Modern browsers,such as Mozilla FireFox and Google Chrome,are equipped with numerous powerful facilities like plug-ins and add-ons,which significantly enrich the user experiences on the Web.However,as Web applications get more complicated day by day,many tedious processes must be performed frequently,while others which are complex or hard to remember are done less frequently.This paper presenb ed the design of Scratch (Smart Capture-and-Replay at Chrome),a collaborative Programming-by-Demonstration (PBD) system for capturing,recording,editing,and playing back the user interactions and sharing user experience in Chrome Web browser,which greatly enhances people’s efficiency.

Key words: Capture and replay,HTML5,Chrome browser,JavaScript