Just-In-Time Defect Prediction on JavaScript Projects: A Replication Study
Bibliographic record
Abstract
Change-level defect prediction is widely referred to as just-in-time (JIT) defect prediction since it identifies a defect-inducing change at the check-in time, and researchers have proposed many approaches based on the language-independent change-level features. These approaches can be divided into two types: supervised approaches and unsupervised approaches, and their effectiveness has been verified on Java or C++ projects. However, whether the language-independent change-level features can effectively identify the defects of JavaScript projects is still unknown. Additionally, many researches have confirmed that supervised approaches outperform unsupervised approaches on Java or C++ projects when considering inspection effort. However, whether supervised JIT defect prediction approaches can still perform best on JavaScript projects is still unknown. Lastly, prior proposed change-level features are programming language–independent, whether programming language–specific change-level features can further improve the performance of JIT approaches on identifying defect-prone changes is also unknown. To address the aforementioned gap in knowledge, in this article, we collect and label the top-20 most starred JavaScript projects on GitHub. JavaScript is an extremely popular and widely used programming language in the industry. We propose five JavaScript-specific change-level features and conduct a large-scale empirical study (i.e., involving a total of 176,902 changes) and find that (1) supervised JIT defect prediction approaches (i.e., CBS+) still statistically significantly outperform unsupervised approaches on JavaScript projects when considering inspection effort; (2) JavaScript-specific change-level features can further improve the performance of approach built with language-independent features on identifying defect-prone changes; (3) the change-level features in the dimension of size (i.e., LT), diffusion (i.e., NF), and JavaScript-specific (i.e., SO and TC) are the most important features for indicating the defect-proneness of a change on JavaScript projects; and (4) project-related features (i.e., Stars, Branches, Def Ratio, Changes, Files, Defective, and Forks) have a high association with the probability of a change to be a defect-prone one on JavaScript projects.
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How this classification was reachedexpand
Direct model labels (unvalidated)
Per-model category and study-design labels from the labeling rounds. They are machine output, unvalidated, and the disagreement between models ships as data. No study design here is MEDLINE-validated yet.
| Model arm | Categories | Study design | Confidence |
|---|---|---|---|
| gemma | no category Domain: not available · Genre: Empirical About the Canadian research system: no · About a Canadian topic: no | Simulation or modeling | high |
| gpt | no category Domain: not available · Genre: Empirical About the Canadian research system: no · About a Canadian topic: no | Observational | high |
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.008 | 0.040 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.004 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.004 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedLabeled directly by 2 models reading the full record.
The models disagree on parts of this classification; every voice is preserved in the section at the end of the page.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".