blinq

A strongly-typed TypeScript implementation of Microsoft dotnet's LINQ to Objects using ES6 iterables.

With the advent of javascript iterators and generators, its possible to pipe sequences through a bunch of transformations without materializing collections (arrays) for the intermediate steps. This library attempts to recreate the dotnet linq-to-objects api to provide a number of standard operations on iterable sequences.

The following operations are available, and the user can optionally supply their own EqualityComparer (implementing equals and getHashCode) when using the set-based operations.

``aggregate, all, any, append, average, concat, count, defaultIfEmpty, distinctBy, distinct, elementAt, except, firstOrDefault, first, flatten, forEach, fullOuterGroupJoin, fullOuterJoin, groupAdjacent, groupBy, groupJoin, intersect, isSubsetOf, isSupersetOf, join, lastOrDefault, last, leftOuterJoin, maxBy, max, minBy, min, orderBy / orderByDescending / thenBy / thenByDescending, preprend, reverse, selectMany, select, sequenceEqual, singleOrDefault, single, skip, skipWhile, sum, take, takeWhile, toArray, toLookup, toMap, toSet, union, where, zipAll, zip`

![Build Status](https://travis-ci.org/biggyspender/blinq)
![Coverage Status](https://coveralls.io/github/biggyspender/blinq?branch=master)

NPM package can be downloaded here.

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Generated documentation can be found at https://biggyspender.github.io/blinq/

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Import blinq ES6 style:

import {
blinq,
range,
empty,
fromGenerator,
fromSingleValue,
repeatGenerate,
repeat,
EqualityComparer,
hashString
} from "blinq";

or nodejs style:

const {
blinq,
range,
empty,
fromGenerator,
fromSingleValue,
repeatGenerate,
repeat,
EqualityComparer,
hashString
} = require("blinq")

Now, just wrap your iterable with a call to blinq(myIterable), and start transforming your data:


const someNumbers = [1, 2, 3, 4];
const squares = blinq(someNumbers).select(n => n * n);
for(let v of squares){
console.log(v);
}

...or if you'd like an array of your results, you can materialize a blinq query with the .toArray() method:

const someNumbers = range(1, 4);
const squaresBelowTen = someNumbers.select(n => n * n).where(n => n < 10);
const arr = squaresBelowTen.toArray();
console.log(arr);

or even spread your results into an array:

const arr2 = [...squaresBelowTen]

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const names = ["zebra", "antelope", "ardvaark", "tortoise", "turtle", "dog", "frog"]
const comparer: EqualityComparer = {
equals: (a, b) => a.toLowerCase() === b.toLowerCase(),
getHashCode: (x) => hashString(x.toLowerCase())
}
const set = blinq(names).toSet(comparer)
expect(set.has("DOg")).toBeTruthy()

#### More examples:

Let's make a collection of cars:

const cars = [{
manufacturer:"Ford",
model:"Escort"
},{
manufacturer:"Ford",
model:"Cortina"
},{
manufacturer:"Renault",
model:"Clio"
},{
manufacturer:"Vauxhall",
model:"Corsa"
},{
manufacturer:"Ford",
model:"Fiesta"
},{
manufacturer:"Fiat",
model:"500"
}
];

...and sort them by manufacturer, and then by model:

const orderedCars = blinq(cars).orderBy(c => c.manufacturer).thenBy(c => c.model);
console.log(orderedCars.toArray());

Or we could count the number of cars for each manufacturer:

const carsPerManufacturer = blinq(cars)
.groupBy(c => c.manufacturer)
.select(g => ({
manufacturer:g.key,
count:g.count()
}))
.orderBy(c => c.manufacturer);
for(var c of carsPerManufacturer){
console.log(${c.manufacturer} : ${c.count}`);
}

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The tests for this project are kept up to date and are the best place to look for other examples.

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Created using the wonderful https://github.com/alexjoverm/typescript-library-starter.