jest-get-type

library29.6.3jsnpmunverified

The `jest-get-type` package provides a core utility function, `getType`, designed to accurately determine the type of any JavaScript value (e.g., 'array', 'object', 'string', 'null', 'undefined', 'function', 'symbol'). It is an integral part of the Jest testing framework's monorepo, ensuring consistent type identification across Jest's various internal components. The current specific package version is 29.6.3, aligning with the Jest 29 ecosystem. However, the broader Jest framework recently released its major version 30.0.0, which targets more frequent major releases after a significant previous gap. This utility is primarily used internally by Jest, but can also be imported directly for robust, Jest-aligned type checking in other projects, especially when consistency with Jest's internal logic is desired. It ships with TypeScript types for an enhanced developer experience.

testing

npm install jest-get-type

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · JEST-GET-TYPE

jest-get-type

testingjavascriptv29.6.3

Install

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Import

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Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

getType

✓ import { getType } from 'jest-get-type';

✗ const getType = require('jest-get-type');

Preferred for modern projects using ESM and TypeScript. Jest 30 generally pushes towards ESM.

getType

✓ const { getType } = require('jest-get-type');

✗ import getType from 'jest-get-type';

For CommonJS environments. This package uses named exports.

GetType

✓ import type { GetType } from 'jest-get-type';

✗ import { GetType } from 'jest-get-type';

Importing the TypeScript type definition for `getType`'s return values or signature.

Demonstrates importing `getType` and using it to determine the type of various JavaScript primitives and objects.

import { getType } from 'jest-get-type'; console.log(getType(1)); // Outputs: 'number' console.log(getType('hello')); // Outputs: 'string' console.log(getType(true)); // Outputs: 'boolean' console.log(getType({})); // Outputs: 'object' console.log(getType([])); // Outputs: 'array' console.log(getType(null)); // Outputs: 'null' console.log(getType(undefined)); // Outputs: 'undefined' console.log(getType(() => {})); // Outputs: 'function' console.log(getType(Symbol('foo'))); // Outputs: 'symbol' interface MyObject { a: number; b: string; } const obj: MyObject = { a: 1, b: 'test' }; console.log(getType(obj)); // Outputs: 'object'

Debug

Known issues

breakingWhen upgrading to Jest 30 (which includes upgrading Jest's sub-packages like `jest-get-type` to v30+), Node.js versions 14, 16, 19, and 21 are no longer supported. Projects must use Node.js 18.x or newer.

fix

Ensure your development and CI/CD environments are running Node.js 18.x or a more recent LTS version before upgrading Jest.

affects: >=30.0.0

breakingProjects upgrading to Jest 30 (and thus `jest-get-type` v30+) must also update their TypeScript version to 5.4 or newer. Using older TypeScript versions with Jest 30 types will result in compilation errors.

fix

Update your TypeScript dependency to `typescript@^5.4.0` or a newer compatible version.

affects: >=30.0.0

gotchaUpgrading to Jest 30 may necessitate regenerating all snapshots due to changes in snapshot header formats and the removal of deprecated `goo.gl` links. While not directly related to `jest-get-type`'s API, it is a common side effect for any project migrating their Jest setup.

fix

After upgrading Jest, run tests with the `-u` flag (`jest -u`) to update all snapshots. Review changes carefully.

affects: >=30.0.0

gotcha`jest-get-type` is primarily an internal utility of the Jest monorepo. While exported, its API and development are driven by Jest's core needs, which may lead to less independent feature development or versioning compared to standalone libraries.

fix

Be aware that direct external dependencies on internal Jest utilities like `jest-get-type` might be subject to changes aligned with Jest's overall architecture rather than external consumer needs. Always check Jest's main changelog for broader context.

affects: >=29.0.0

Errors

Common errors & fixes

TypeError: (0, jest_get_type_1.getType) is not a function

Incorrect import statement when mixing CommonJS and ESM modules, or trying to default import a named export.

fix

If using CommonJS, ensure `const { getType } = require('jest-get-type');`. If using ESM, ensure `import { getType } from 'jest-get-type';`. Do not use `import getType from 'jest-get-type';` as it is not a default export.

Jest requires Node.js 18 or newer.

Running a project with Jest 30 (or `jest-get-type` v30+) on an unsupported Node.js version.

fix

Upgrade your Node.js environment to version 18.x or higher. Check your project's `.nvmrc` or CI/CD configuration.

TS2307: Cannot find module 'jest-get-type' or its corresponding type declarations.

Missing `@types/jest` or `jest-get-type` package, or incorrect TypeScript configuration.

fix

Ensure `jest-get-type` and `@types/jest` (if Jest is also installed) are in your `devDependencies`. Verify `tsconfig.json` includes `node_modules/@types` in `typeRoots` and `moduleResolution` is set appropriately (e.g., `bundler`, `node16`, or `nodenext`).

Upgrade

Version history

29.6.3latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/jestjs/jest ↗

packagehttps://www.npmjs.com/package/jest-get-type ↗

homepagehttps://jestjs.io ↗