Implementing Mutual Exclusion for AJAX

(Bruce Wallace) With the increasingly popular AJAX paradigm, a browser page can make requests for server data in the background while the user interface continues to be active in the foreground (hence the "asynchronous" in AJAX). However, the problem exists that these two activities are typically accessing common JavaScript and DOM data structures simultaneously. The classic solutions to this concurrent programming problem are not supplied by JavaScript. This article describes the author's new adaptation of a proven mutual exclusion mechanism that works around the limitations of JavaScript.