Registry / testing / eslint-type-tracer

eslint-type-tracer

library0.5.2jsnpmunverified

A utility for inferring runtime types of expression nodes within ESLint rules, enabling type-aware linting without a full TypeScript type checker. Version 0.5.2 is the latest stable release with support for Temporal, Math.sumPrecise(), well-known symbols, and improved type definitions. It is published under MIT license and maintained by ota-meshi. Key differentiators: lightweight, no external runtime dependencies, limited to single-file analysis (no cross-module inference), and exports ESM via .mjs extension. Designed for ESLint v8.57+, Node.js >=18. Typical use cases include validating arrays, strings, numbers, and other built-in types inside ESLint rule implementations.

testing

npm install eslint-type-tracer

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · ESLINT-TYPE-TRACER

eslint-type-tracer

testingjavascriptv0.5.2

Install

—

Import

—

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.

buildTypeTracer

✓ import { buildTypeTracer } from 'eslint-type-tracer'

✗ const { buildTypeTracer } = require('eslint-type-tracer')

Since v0.5.1, package uses .mjs extension. CommonJS require() still works if the runtime supports it, but ESM import is preferred.

buildTypeChecker

✓ import { buildTypeChecker } from 'eslint-type-tracer'

✗ import buildTypeChecker from 'eslint-type-tracer'

Default import is not supported. Only named exports are available.

TypeName

✓ import type { TypeName } from 'eslint-type-tracer'

TypeName is a type exported for TypeScript users; it is not a runtime value. Use type import.

Creates an ESLint rule that uses buildTypeTracer to infer the type of the object in a member expression and reports if it is an Array.

import { buildTypeTracer } from 'eslint-type-tracer'; import type { Rule } from 'eslint'; const myRule: Rule.RuleModule = { create(context) { const typeTrace = buildTypeTracer(context.sourceCode); return { CallExpression(node) { const callee = node.callee; if (callee.type === 'MemberExpression') { const objectTypeNames = typeTrace(callee.object); if (objectTypeNames.includes('Array')) { context.report({ node, message: 'Array method called.' }); } } } }; } }; export default myRule;

Debug

Known issues

breakingIn v0.5.0, support for Temporal was added, which may cause breakage if your code expects previous behavior with Date-like types now being inferred as Temporal types.

fix

Update to v0.5.2 or later where Temporal definitions were improved.

affects: >=0.5.0 <0.5.2

breakingIn v0.2.0, the API was redesigned. The previous default export or function signatures are removed.

fix

Migrate to v0.2.0+ using buildTypeTracer and buildTypeChecker.

affects: <0.2.0

deprecatedThe package is ESM-first starting v0.5.1. CommonJS require may still work but is not officially supported and may break in future versions.

fix

Switch to ESM imports ('import { ... } from "eslint-type-tracer"') or use dynamic import.

affects: >=0.5.1

gotchaType inference is limited to the current file only. Cross-module types cannot be inferred.

fix

Do not rely on the tool for cross-module inference; consider using TypeScript's type checker if needed.

affects: >=0.1.0

Errors

Common errors & fixes

Error [ERR_REQUIRE_ESM]: require() of ES Module ... from ... not supported.

Since v0.5.1, the package exports ES modules (.mjs) and CommonJS require() is not natively supported in older Node versions.

fix

Use dynamic import: const { buildTypeTracer } = await import('eslint-type-tracer'); or use ESM in your project.

Cannot find module 'eslint-type-tracer' or its corresponding type declarations.

TypeScript cannot find types if the package is not installed or if the import path is wrong.

fix

Ensure eslint-type-tracer is installed and that you are using the correct import: import { buildTypeTracer } from 'eslint-type-tracer'.

Upgrade

Version history

0.5.2latest on npm

Audit

Dependencies

eslintrequiredPeer dependency: the package is designed to work as an ESLint plugin utility and requires ESLint v8.57+

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/ota-meshi/eslint-type-tracer ↗

packagehttps://www.npmjs.com/package/eslint-type-tracer ↗

homepagehttps://ota-meshi.github.io/eslint-type-tracer/ ↗