1. A computer-implemented method of capturing transaction data associated with a purchase made by a user on a client computer running a web browser client process and coupled over the Internet to an e-commerce server system, wherein the browser client process includes a script-generated process based on an e-commerce script served to the browser client process, the e-commerce script enabling e-commerce actions performed by the user including adding an item to a shopping cart and entering an execute purchase command that causes sending of a consummate-purchase command to the e-commerce server system, the method comprising: serving to the browser client process a capture script, the capture script configured to perform processes of (i) attaching action listeners to monitor specified ones of the e-commerce actions and (ii) causing creation of an event log of the monitored e-commerce actions, wherein each such action listener is configured to write its corresponding action to the event log when such action has occurred, and (iii) causing sending of the event log to an event server system.