%0 Conference Paper %1 Bogner2022 %A Bogner, Justus %A Merkel, Manuel %B 2022 IEEE/ACM 19th International Conference on Mining Software Repositories (MSR) %D 2022 %K iste-se myown %P 658--669 %R 10.1145/3524842.3528454 %T To Type or Not to Type? A Systematic Comparison of the Software Quality of JavaScript and TypeScript Applications on GitHub %X JavaScript (JS) is one of the most popular programming languages, and widely used for web apps, mobile apps, desktop clients, and even backend development. Due to its dynamic and flexible nature, however, JS applications often have a reputation for poor software quality. While the type-safe superset TypeScript (TS) offers features to address these prejudices, there is currently insufficient empirical evidence to broadly support the claim that TS applications exhibit better software quality than JS applications. We therefore conducted a repository mining study based on 604 GitHub projects (299 for JS, 305 for TS) with over 16M LoC. Using SonarQube and the GitHub API, we collected and analyzed four facets of software quality: a) code quality (\# of code smells per LoC), b) code understandability (cognitive complexity per LoC), c) bug proneness (bug fix commit ratio), and d) bug resolution time (mean time a bug issue is open). For TS, we also collected how frequently the type-safety ignoring any type was used per project via ESLint. The analysis indicates that TS applications exhibit significantly better code quality and understandability than JS applications. Contrary to expectations, however, bug proneness and bug resolution time of our TS sample were not significantly lower than for JS: the mean bug fix commit ratio of TS projects was more than 60\% larger (0.126 vs. 0.206), and TS projects needed on average more than an additional day to fix bugs (31.86 vs. 33.04 days). Furthermore, reducing the usage of the any type in TS apps appears to be beneficial: its frequency was significantly correlated with all metrics except bug proneness, even though the correlations were of small strengths (Spearman's rho between 0.17 and 0.26). Our results indicate that the perceived positive influence of Type-Script for avoiding bugs in comparison to JavaScript may be more complicated than assumed. While using TS seems to have benefits, it does not automatically lead to less and easier to fix bugs. However, more research is needed in this area, especially concerning the potential influence of project complexity and developer experience.

@inproceedings{Bogner2022, abstract = {JavaScript (JS) is one of the most popular programming languages, and widely used for web apps, mobile apps, desktop clients, and even backend development. Due to its dynamic and flexible nature, however, JS applications often have a reputation for poor software quality. While the type-safe superset TypeScript (TS) offers features to address these prejudices, there is currently insufficient empirical evidence to broadly support the claim that TS applications exhibit better software quality than JS applications. We therefore conducted a repository mining study based on 604 GitHub projects (299 for JS, 305 for TS) with over 16M LoC. Using SonarQube and the GitHub API, we collected and analyzed four facets of software quality: a) code quality (\# of code smells per LoC), b) code understandability (cognitive complexity per LoC), c) bug proneness (bug fix commit ratio), and d) bug resolution time (mean time a bug issue is open). For TS, we also collected how frequently the type-safety ignoring any type was used per project via ESLint. The analysis indicates that TS applications exhibit significantly better code quality and understandability than JS applications. Contrary to expectations, however, bug proneness and bug resolution time of our TS sample were not significantly lower than for JS: the mean bug fix commit ratio of TS projects was more than 60\% larger (0.126 vs. 0.206), and TS projects needed on average more than an additional day to fix bugs (31.86 vs. 33.04 days). Furthermore, reducing the usage of the any type in TS apps appears to be beneficial: its frequency was significantly correlated with all metrics except bug proneness, even though the correlations were of small strengths (Spearman's rho between 0.17 and 0.26). Our results indicate that the perceived positive influence of Type-Script for avoiding bugs in comparison to JavaScript may be more complicated than assumed. While using TS seems to have benefits, it does not automatically lead to less and easier to fix bugs. However, more research is needed in this area, especially concerning the potential influence of project complexity and developer experience.}, added-at = {2022-11-03T10:34:04.000+0100}, author = {Bogner, Justus and Merkel, Manuel}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2e82be6fead7f255acbbebd4bfb84214b/justusbogner}, booktitle = {2022 {{IEEE}}/{{ACM}} 19th {{International Conference}} on {{Mining Software Repositories}} ({{MSR}})}, copyright = {All rights reserved}, doi = {10.1145/3524842.3528454}, file = {C\:\\Users\\JREB\\Zotero\\storage\\H7TGYZSV\\Bogner and Merkel - 2022 - To Type or Not to Type A Systematic Comparison of.pdf;C\:\\Users\\JREB\\Zotero\\storage\\GCZPIWHG\\9796341.html}, interhash = {f10abe26ff52dd1bb24cfc28445dfdde}, intrahash = {e82be6fead7f255acbbebd4bfb84214b}, issn = {2574-3864}, keywords = {iste-se myown}, month = may, pages = {658--669}, shorttitle = {To {{Type}} or {{Not}} to {{Type}}?}, timestamp = {2022-11-03T09:34:04.000+0100}, title = {To {{Type}} or {{Not}} to {{Type}}? {{A Systematic Comparison}} of the {{Software Quality}} of {{JavaScript}} and {{TypeScript Applications}} on {{GitHub}}}, year = 2022 }