JSCert: Certifying JavaScript

Presented as part of the 2013 HCSS conference.

ABSTRACT

JavaScript has become the most widely used language for client- side web programming. The dynamic nature of JavaScript makes understanding its code notoriously difficult, leading to buggy programs and a lack of adequate static-analysis tools. We believe that logical reasoning has much to offer JavaScript: a simple description of program behaviour, a clear understanding of module boundaries, and the ability to verify security contracts.

We introduce a program logic for reasoning about a broad subset of JavaScript, including challenging features such as prototype inheritance and with. We adapt ideas from separation logic to provide tractable reasoning about JavaScript code: reasoning about easy programs is easy; reasoning about hard programs is possible. We prove a strong soundness result. All libraries written in our subset and proved correct with respect to their specifications will be well-behaved, even when called by arbitrary JavaScript code.