Abstract
As the usage of JavaScript is taking over web applications, application development, and server side scripting, JavaScript's conciseness is a very important aspect of the language. Static analysis of JavaScript code is very difficult to preform due to the dynamic nature of JavaScript. The JavaScript Abstract Interpreter (JSAI) is designed to be provably sound with respect to a specific concrete semantics for JavaScript, which has been extensively tested against a commercial JavaScript implementation. The built-in domain for String analysis that comes with JSAI distribution is a constant propagation domain. The project will replace the constant propagation domain with the domain of Finite State Automata (FSA). The implementation of string domain using FSA will increase JSAI string domain precision by returning a machine that represents all possible values.