https://github.com/aaronpowell/linq-in-javascript

An implementation of LINQ in JavaScript use ES6 iterators for proper lazy evaluation
https://github.com/aaronpowell/linq-in-javascript

Last synced: about 1 month ago
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An implementation of LINQ in JavaScript use ES6 iterators for proper lazy evaluation

• Host: GitHub
• URL: https://github.com/aaronpowell/linq-in-javascript
• Owner: aaronpowell
• License: mit
• Created: 2013-07-16T00:43:32.000Z (over 11 years ago)
• Default Branch: master
• Last Pushed: 2020-11-22T23:56:45.000Z (about 4 years ago)
• Last Synced: 2024-11-17T19:45:21.755Z (about 2 months ago)
• Language: JavaScript
• Size: 103 KB
• Stars: 81
• Watchers: 8
• Forks: 16
• Open Issues: 3
• Metadata Files:
  • Readme: readme.md
  • License: license.md

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README

        
# LINQ in JavaScript

I write a lot of C# and it has a really useful way to query large collections of data, called [LINQ](https://msdn.microsoft.com/library/vstudio/bb397926.aspx?WT.mc_id=javascript-0000-aapowell).

Although JavaScript arrays have querying capabilities through `map`, `reduce`, `filter` but the limitation is they process the entire array before going to the next step, meaning if you do a `map` then a `filter` the whole collection goes through map process before it starts filtering. This can be a problem with large data sets, it can take a while.

## Why LINQ?

The advantage of LINQ is that it uses lazy execution, each item goes through the whole _pipeline_ before the next item is processed. So if you have a large data set you can easily process subsets of the data and break early.

## How does it work?

To do this it leverages the [ES6 Iterators](http://wiki.ecmascript.org/doku.php?id=harmony:iterators) to `yield` each value.

# Example

```javascript

var items = [1, 2, 3, 4, 5, 6].asEnumerable();

for (let item in items.where(x => x % 2).select(x => x + 1))

    console.log(item);

//output will be 2, 4, 6

```

# API

The following LINQ methods are implemented:

* `aggregate`

* `all`

* `any`

* `asEnumerable`

* `average`

* `concat`

* `contains`

* `count`

* `first`, `firstOrDefault`

* `range`

* `repeat`

* `select`, aliased to `map`

* `selectMany`

* `single`, `singleOrDefault`

* `toArray`

* `where`, aliased to `filter`

_The full list of what LINQ in .NET does can be found [here](https://msdn.microsoft.com/library/system.linq.enumerable_methods?WT.mc_id=javascript-0000-aapowell(v=vs.110).aspx)._

# License

MIT