LINQ for JavaScript & jQuery

If you are familiar with C#, you probably use LINQ on a daily basis. But did you ever dream using it in your client's code. I use a lot of JavaScript in applications I develop mostly making use of jQuery library and more than once I did wished to be able to use a LINQ on client side.

Today I was facing a dilemma of querying a lot of data in JavaScript and JSON again. I did a little search and find out that there is actually a solution that allows me to use LINQ in my script.

It is called linq.js and resides on Codeplex

This library seems like a serious development effort with a lot of features. Here are some of them.
- Implement all .NET 4.0 methods
- Implement many extra methods inspired by Rx, Ruby and others
- Complete lazy evaluation
- Full IntelliSense support for VisualStudio
- Two versions - linq.js and jquery.linq.js (jQuery plugin)
- Support Windows Script Host
- Binding for Reactive Extensions for JavaScript(RxJS) and IntelliSense Generator

It's almost too good to be true, isn't it. You can see a full reference here

And here are some examples to catch your eye.

A basic one

var jsonArray = [
    { "user": { "id": 100, "screen_name": "d_linq" }, "text": "to objects" },
    { "user": { "id": 130, "screen_name": "c_bill" }, "text": "g" },
    { "user": { "id": 155, "screen_name": "b_mskk" }, "text": "kabushiki kaisha" },
    { "user": { "id": 301, "screen_name": "a_xbox" }, "text": "halo reach" }
]
// ["b_mskk:kabushiki kaisha", "c_bill:g", "d_linq:to objects"]
var queryResult = Enumerable.From(jsonArray)
    .Where(function (x) { return x.user.id < 200 })
    .OrderBy(function (x) { return x.user.screen_name })
    .Select(function (x) { return x.user.screen_name + ':' + x.text })
    .ToArray();
// shortcut! string lambda selector
var queryResult2 = Enumerable.From(jsonArray)
    .Where("$.user.id < 200")
    .OrderBy("$.user.screen_name")
    .Select("$.user.screen_name + ':' + $.text")
    .ToArray();

See how close it is to C#

// C# LINQ (delegate)
Enumerable.Range(1, 10)
    .Where(delegate(int i) { return i % 3 == 0; })
    .Select(delegate(int i) { return i * 10; });
// linq.js - anonymous function
Enumerable.Range(1, 10)
    .Where(function(i) { return i % 3 == 0; })
    .Select(function(i) { return i * 10; });

// C# LINQ (lambda)
Enumerable.Range(1, 10).Where(i => i % 3 == 0).Select(i => i * 10);
// linq.js - lambda expression
Enumerable.Range(1, 10).Where("i => i % 3 == 0").Select("i => i * 10");

// $ is default iterator variable like Scala's "_" or Groovy's "it"
Enumerable.Range(1, 10).Where("$ % 3 == 0").Select("$ * 10");
 // "" is shortcut of "x => x" (identity function)
Enumerable.Range(4, 7).Join(Enumerable.Range(8, 5), "", "", "outer,inner=>outer*inner");

// Enumerable.From is wrap from primitive array, string(to charArray), object(to KeyValuePair[]) etc..
var array = [100, 200, 30, 40, 500, 40, 200];
var ex1 = Enumerable.From(array).Distinct().ToArray(); // [100, 200, 30, 40, 500]
var ex2 = Enumerable.From("foobar").ToArray(); // ["f", "o", "o", "b", "a", "r"];
var ex3 = Enumerable.From({foo:10, bar:20}).ToArray(); // [{Key:"foo",Value:10}, {Key:"bar",Value:20}]

// C# - AnonymousType
array.Select((val, i) => new { Value = val, Index = i });
// linq.js - object literal
Enumerable.From(array).Select("val,i=>{Value:val, Index:i}")

It comes as a jQuery plugin as well. Which seems like a great option to me.

// $.Enumerable
$.Enumerable.Range(1, 10).Where("$%2==0").ForEach("alert($)");

// TojQuery - Enumerable to jQuery
$.Enumerable.Range(1, 10)
    .Select(function (i) { return $("").text(i) })
    .TojQuery()
    .appendTo("#select1");

// toEnumerable - jQuery to Enumerable
var sum = $("#select1").children()
    .toEnumerable()
    .Select("parseInt($.text())")
    .Sum(); // 55

In overall this looks very good and states on a great new possibilities to those who creates serious applications with a lot of client side coding.
Performance, actual compatibility, convenience and other possible issues should still be checked, but no doubt that for those of us who know and love LINQ in C#, it's awesome that we can have client-side LINQ methods available.

Great job!