linqts

library3.2.0jsnpmunverified

linqts is a TypeScript library that ports LINQ (Language Integrated Query) capabilities, familiar to C# developers, to JavaScript and TypeScript environments. It provides a `List<T>` class that offers a rich set of methods for querying and manipulating collections in a fluent, declarative style, including operations like `Where`, `Select`, `Join`, `GroupBy`, `Min`, and `Max`. The library is currently stable at version 3.2.0 and maintains an active development cadence with major releases approximately annually and more frequent minor and patch updates addressing features and bug fixes. Its primary differentiator is the direct porting of the LINQ API surface, which makes it intuitive for developers coming from a .NET background, providing strong type safety through TypeScript.

data serialization

npm install linqts

github ↗package ↗

INSTALL

IMPORT

SIG · LINQTS

linqts

datajavascriptv3.2.0

Install

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Import

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Disk

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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.

List

✓ import { List } from 'linqts';

✗ const List = require('linqts').List;

The `List` class is the primary export and entry point for all LinQ-like operations. It's intended for ESM and TypeScript usage. For CommonJS, `require('linqts').List` is the typical access pattern.

ListConstructor

✓ import { List } from 'linqts'; new List<MyType>(myArray);

✗ import List from 'linqts'; new List<MyType>(myArray);

The `List` class is a named export, not a default export. Attempting to import it as a default will result in an undefined `List`.

Iterable/Spread

✓ import { List } from 'linqts'; const myList = new List([1,2,3]); [...myList]

✗ import { List } from 'linqts'; const myList = new List([1,2,3]); for (const item of myList) {}

Since v1.15.0, `List` instances are iterable, allowing use with `for...of` loops and spread syntax. Older versions may not support this directly.

This quickstart demonstrates basic filtering, mapping, and joining operations using the `List` class to perform LinQ-style queries on in-memory collections.

import { List } from 'linqts'; interface Person { Name: string; Age: number; } interface Pet { Name: string; Owner: Person; Type: string; } const people: Person[] = [ { Name: 'Alice', Age: 30 }, { Name: 'Bob', Age: 25 }, { Name: 'Charlie', Age: 35 } ]; const pets: Pet[] = [ { Name: 'Fido', Owner: people[0], Type: 'Dog' }, { Name: 'Whiskers', Owner: people[1], Type: 'Cat' }, { Name: 'Buddy', Owner: people[0], Type: 'Dog' } ]; // Example 1: Filtering and mapping const youngAdultsNames = new List(people) .Where(p => p.Age < 30) .Select(p => p.Name) .ToArray(); console.log('Young Adults Names:', youngAdultsNames); // Expected: ['Bob'] // Example 2: Joining collections const petsByOwner = new List(people).Join( pets, person => person, pet => pet.Owner, (person, pet) => ({ OwnerName: person.Name, PetName: pet.Name, PetType: pet.Type }) ); console.log('Pets by Owner:', petsByOwner.ToArray()); /* Expected: [ { OwnerName: 'Alice', PetName: 'Fido', PetType: 'Dog' }, { OwnerName: 'Bob', PetName: 'Whiskers', PetType: 'Cat' }, { OwnerName: 'Alice', PetName: 'Buddy', PetType: 'Dog' } ]*/

Debug

Known issues

breakingThe `Min()` and `Max()` functions are now generic. Code relying on the non-generic versions or specific type inference may require updates.

fix

Review calls to `Min()` and `Max()` to ensure correct generic type arguments or selectors are provided, especially if working with complex objects. For example, `list.Min(x => x.property)`.

affects: >=3.0.0

breakingThe behavior of `ToDictionary()` and all `*OrDefault()` functions (e.g., `FirstOrDefault()`, `SingleOrDefault()`) changed significantly, primarily due to stricter TypeScript support. Additionally, strict mode support was introduced.

fix

Carefully test existing code that uses `ToDictionary()` or any `*OrDefault()` methods. Update logic if their new behavior (especially regarding default values for `*OrDefault` and key collisions for `ToDictionary`) no longer aligns with assumptions. Ensure your `tsconfig.json` is configured correctly for strict mode if enabling it.

affects: >=2.0.0

gotcha`ElementAtOrDefault()` was fixed to return `undefined` when the index is out of range, instead of throwing an error. This is a behavioral change.

fix

If your code previously relied on `ElementAtOrDefault()` throwing an error for out-of-range indices, you must update it to explicitly check for `undefined` return values.

affects: >=1.14.0

gotchaOlder versions (prior to v1.14.4) had issues with module resolution for TypeScript projects when building for CommonJS, potentially causing errors.

fix

Ensure you are using `linqts@1.14.4` or newer to avoid potential CommonJS module resolution issues in TypeScript projects.

affects: <1.14.4

Errors

Common errors & fixes

TypeError: list.Min is not a function or TypeError: Argument of type '(x: SomeType) => string' is not assignable to parameter of type '((arg: T) => number) | undefined'

Attempting to use `Min()` or `Max()` without providing a selector function or incorrect generic types after v3.0.0 made these methods generic.

fix

Provide a selector function to `Min()` or `Max()` to specify the property to compare, e.g., `list.Min(item => item.value)`.

TypeError: Cannot read properties of undefined (reading 'Where') or TypeError: List is not a constructor

Incorrect import statement for the `List` class, often attempting to use a default import instead of a named import, or incorrect CommonJS require.

fix

Ensure you use `import { List } from 'linqts';` for ESM/TypeScript or `const { List } = require('linqts');` for CommonJS.

Property 'ToDictionary' does not exist on type 'List<MyType>' or runtime error with unexpected `ToDictionary` behavior.

Usage of `ToDictionary()` with an incorrect signature or misunderstanding its updated behavior after v2.0.0, especially regarding strict mode implications or key uniqueness.

fix

Consult the `linqts` documentation for `ToDictionary()` in version 2.0.0 and above. Ensure your key selector returns unique keys or handle potential collisions as per the new behavior.

Upgrade

Version history

3.2.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

6 hits · last 30 days

node

Resources

githubhttps://github.com/kutyel/linq.ts ↗

packagehttps://www.npmjs.com/package/linqts ↗