Improving Tools for JavaScript Programmers (Position Paper) Esben Andreasen Asger Feldthaus Simon Holm Jensen Aarhus University Aarhus University Aarhus University
[email protected] [email protected] [email protected] Casper S. Jensen Peter A. Jonsson Magnus Madsen Aarhus University Aarhus University Aarhus University
[email protected] [email protected] [email protected] Anders Møller Aarhus University
[email protected] ABSTRACT 2. FINDING ERRORS WITH We present an overview of three research projects that all DATAFLOW ANALYSIS aim to provide better tools for JavaScript web application 1 The TAJS analysis tool infers an abstract state for each programmers : TAJS, which infers static type information program point in a given JavaScript web application. Such for JavaScript applications using dataflow analysis; JSRefac- an abstract state soundly models the possible states that tor, which enables sound code refactorings; and Artemis, may appear at runtime and can be used for detecting type- which provides high-coverage automated testing. related errors and dead code. These errors often arise from wrong function parameters, misunderstandings of the run- time type coercion rules, or simple typos that can be tedious to find using testing. 1. JAVASCRIPT PROGRAMMERS NEED We have approached the development of TAJS in stages. BETTER TOOLS First, our focus has been on the abstract domain and dataflow JavaScript contains many dynamic features that allegedly constraints that are required for a sound and reasonably ease the task of programming modern web applications. Most precise modeling of the basic operations of the JavaScript importantly, it has a flexible notion of objects: properties are language itself and the native objects that are specified in added dynamically, the names of the properties are dynam- the ECMAScript standard [3].