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Jest — JavaScript testing with watch mode and snapshot comparisons

Discovery score 324.9OSS health 96
About these scores

Discovery score is an unbounded weighted, log-compressed index of stars, watchers, forks, and contributors. Growth momentum is its change over the observed period; OSS health is a 0–100 score from available repository recency, Community Health, and release data.

Stars
45,457
Primary language
TypeScript
License
MIT
Repository last updated
Sep 10, 2026

Overview

Jest is a testing framework designed to work out of the box for many JavaScript projects. It combines expect assertions, a watch mode that runs tests related to changed files, snapshot testing for large values, a CLI, and configuration support.

Based on official documentation; not hands-on tested · Content checked:

Combine assertions, change tracking, and repeated test runs

Tests and expect assertions describe results, while watch mode narrows execution to tests related to changed files. Snapshots preserve large object states for comparison. The README also covers the CLI, configuration generation, Babel, webpack, Parcel, and TypeScript setup.

Sources: [1]

For standardizing unit and integration testing in JavaScript

It fits teams bringing test syntax, a runner, iterative watch behavior, and snapshots into one tool for Node.js and frontend projects. Jest installs as a development dependency through npm or Yarn.

Sources: [1]

Design TypeScript checking and Vite integration separately

Babel-based TypeScript support transpiles code but does not type-check tests. Type checking requires ts-jest or a separate tsc step. Vite is not fully supported because of its plugin system, so review the available integration examples and limitations before selecting a configuration.

Sources: [1]

Official sources

  1. [1]Jest README(2026-09-13)
Supplemental curator note

Selected for a peaceful Meta-to-OpenJS transfer and an adoption footprint and comparison demand much larger than recent star growth suggests.

Growth trends

Last 30 days

45,457 Stars

Trend data is still being collected.

Built with

  • TypeScript
  • JavaScript

Categories and tags

Categories

Tags

GitHub Topics

  • javascript
  • testing
  • painless-javascript-testing
  • facebook
  • immersive
  • painless
  • expectation
  • easy
  • snapshot
GitHub dataView detailed GitHub data
View on GitHub
Stars
45,457
Forks
6,727
Watchers
598
Open issues
137
Contributors
426
Primary language
TypeScript
License
MIT
Repository last updated
Sep 10, 2026
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