A linter is a type of static analysis tool that warns software developers about pos- sible errors in code or violations to coding standards. By using such a tool, errors can be surfaced early in the development process when they are cheaper to fix, and code can be kept more readable and maintainable. For such a tool to be successful, it is important for its creators to understand the needs and challenges of developers when using a linter. Furthermore, it needs to be made clear to developers why using such a tool can be beneficial, along with how linters can be configured to identify appropriate and relevant issues for their projects.
In this thesis, we examine developers’ perceptions of linters to increase our knowl- edge on these tools for JavaScript, the most widely used programming language in the world today. More specifically, we study why and how developers use ESLint, the most popular JavaScript linter, along with the challenges that they face while using the tool. We collect data with three different methods where we first interview 15 experts on using linters, then analyze over 9,500 ESLint configuration files and finally survey more than 300 developers from the JavaScript community. The combined results from these analyses provide developers, tool makers and researchers with valuable knowl- edge and advice on using and developing a linter for JavaScript.