Linq4JS

Linq methods for JavaScript/TypeScript for working with arrays

This simple extension works with array of complex objects as well as simple arrays of strings etc. The whole thing is written in TypeScript but also usable in JavaScript

Advantages

This extension is lightweight and fast and you can use your Lambda-Expression-Syntax to work with arrays. The methods are mostly identically to .NET methods.

As expressions you can use the normal Function-Syntax:

array.Where(function(x){
	return x.Name == "Max";
});

Lambda-Expressions (IE isn't compatible with this Lambda-Expressions):

array.Where(x => x.Name == "Max");

or Lambda-Expressions as Strings (this Syntax works in IE):

array.Where("x => x.Name == 'Max'");

SQL-Like

Also a complete procedure as an sql-like string is supported

array.Evaluate("select x => x.Id sum");

clone
reverse
where x => x.Age > 70
order by x => x.Name
then by x => x.FirstName descending
for each x => console.log(x)
select x => {x.Name}

Conclusion

• Works with multiple Browsers (even IE)
• Angular Support (event directly in Views if using Strings as Expression-Syntax)
• Lightweight
• Fast
• Syntax from .NET
• Build on top of array-prototype and no changes in code are required for usage
• Integrates seamlessly into the project
• TypeScript definitions

Getting Started

Install using NPM

npm install linq4js

Install using Bower

bower install linq4js

Using JavaScript

Include this line in your project

<script type="text/javascript" src="linq4js.js"></script>

Using TypeScript

Use

import "linq4js";

or

<script type="text/javascript" src="linq4js.js"></script>

to import the scripts and optionally (if you are not using npm) install @types/linq4js to also get tooling support.

Usage

Clone

Creates a copy of the array

var array = ["item1", "item2", "item3", "item4", "no"];

//["item1", "item2", "item3", "item4", "no"]
array.Clone();

FindIndex

Gets the index of the first item found by a filter

var array = ["item1", "item2", "item3", "item4", "no"];

//2
array.FindIndex("x => x == 'item3'");

FindLastIndex

Gets the index of the last item found by a filter

var array = ["item1", "item2", "item3", "item2", "item4", "no"];

//3
array.FindIndex("x => x == 'item2'");

Get

Gets the item with the index

var array = ["item1", "item2", "item3", "item4", "no"];

//"item3"
array.Get(2);

Repeat

Repeats an object in the array

var array = ["item1", "item2", "item3", "item4"];

//["item1", "item2", "item3", "item4", "example", "example", "example"]
array.Repeat("example", 3);

ForEach

Executes a method for each item in the array

var array = ["item1", "item2", "item3", "item4", "no"];
array.ForEach("i => console.log(i)");

Update & UpdateRange

Updates object(s) in the array

By default this method uses the property Id to identify the objects. If the property is not set this methods tries to compare the objects directly.

var array = [{Id: 1, Value: "item1"}, {Id: 2, Value: "item2"}];
	
//[{Id: 1, Value: "item3"}, {Id: 2, Value: "item2"}]
array.Update({Id: 1, Value: "item3"});

If you want this method to use other fields for identification define a selector function as second parameter.

var array = [{OtherId: 1, Value: "item1"}, {OtherId: 2, Value: "item2"}];
	
//[{Id: 1, Value: "item3"}, {Id: 2, Value: "item2"}]
array.Update({OtherId: 1, Value: "item3"}, "x => x.OtherId");

You can upgrade multiple objects simultaneously

var array = [{OtherId: 1, Value: "item1"}, {OtherId: 2, Value: "item2"}];
	
//[{Id: 1, Value: "item3"}, {Id: 2, Value: "item4"}]
array.UpdateRange(
	[{OtherId: 1, Value: "item3"}, {OtherId: 2, Value: "item4"}], 
	"x => x.OtherId");

Remove & RemoveRange

Removes item(s) from array

By default this method uses the property Id to identify the objects. If the property is not set this methods tries to compare the objects directly.

var array = ["item1", "item2", "item3", "item4", "no"];

//["item1", "item2", "item3", "item4"]
array.Remove("no");
	
//["item1", "item2"]
array.RemoveRange(["item4", "item3"]);

If you want this method to use other fields for identification define a selector function as second parameter.

var array = [{OtherId: 1, Value: "item1"}, {OtherId: 2, Value: "item2"}];

//[{OtherId: 2, Value: "item2"}]
array.Remove({OtherId: 1}, "x => x.OtherId");

Add & AddRange

Adds the item(s) to the array

var array = ["item1", "item2", "item3", "item4", "no"];

//["item1", "item2", "item3", "item4", "no", "item5"]
array.Add("item5");

//["item1", "item2", "item3", "item4", "no", "item5", "item6", "item7"]
array.AddRange(["item6", "item7"]);

Insert

Inserts an entry at a specific position

var array = ["item1", "item2", "item3", "item4"];

//["item1", "item2", "item2.5", "item3", "item4"]
array.Insert("item2.5", 2);

Where

Searches for all items in array that match the given filter

var array = ["item1", "item2", "item3", "item4", "no"];

//["item1", "item2", "item3", "item4"]
array.Where("i => i.match(/item/gi)");

Range

Takes items in a specific range

var array = ["item1", "item2", "item3", "item4"];

//["item2", "item3"]
array.Range(1, 2);

Count

Returns the length of the array or if a filter is set the length of the resulting array

var array = ["item1", "item2", "item3", "item4", "no"];

//5
array.Count();

//4
array.Count("i => i.match(/item/gi)");

SequenceEqual

Compares to sequences of objects

var array = ["item1", "item2", "item3"];
var array2 = ["item1", "item2", "item3"];
var array3 = ["item", "item2", "item3"];

//true
array.SequenceEqual(array2);

//false
array.SequenceEqual(array3);

Any

Tests if any item is in the array and if a filter is set if any item of the array matches the filter

var array = ["item1", "item2", "item3", "item4", "no"];

//true
array.Any();

//true
array.Any("i => i.length > 2");
	
//false
array.Any("i => i == ''");

All

Tests if all items in the array match the condition

var array = ["item1", "item2", "item3", "item4", "no"];

//false
array.All("i => i.length > 2");

Contains

Tests if array contains specific object

var array = ["item1", "item2", "item3", "item4", "no"];

//false
array.Contains("test");

Concat

Combines two arrays

var array = ["item1", "item2", "item3"];
var array2 = ["item4", "no"];

//["item1", "item2", "item3", "item4", "no"]
array.Concat(array2);

Intersect

Combines two arrays but only applies values that are in both arrays

var array = ["item1", "item2", "item3"];
var array2 = ["item1", "unique", "item2", "item3"];

//["item1", "item2", "item3"]
array.Intersect(array2);

Union

Combines two arrays without duplicates

var array = ["item1", "item2", "item3"];
var array2 = ["item1", "unique", "item2", "item3"];

//["item1", "item2", "item3", "unique"]
array.Union(array2);

Join

Joins the entries by the given char

var array = ["item1", "item2", "item3", "item4", "no"];

//item1-item2-item3-item4-no
array.Join("-");

//item1-item2-item3-item4
array.Join("-", "x => x.length > 2");

Aggregate

Combines the entries using a custom function

var array = ["item1", "item2", "item3", "item4", "no"];

//no-item4-item3-item2-item1
array.Aggregate("(str, item) => item + '-' + item");

ToDictionary

Converts the array to a dictionary

var array = [{OtherId: 1, Value: "item1"}, {OtherId: 2, Value: "item2"}];

//{1: {OtherId: 1, Value: "item1"}, 2: {OtherId: 2, Value: "item2"}}
array.ToDictionary("x => x.OtherId");

//{1: "item1", 2: "item2"}
array.ToDictionary("x => x.OtherId", "x => x.Value");

Zip

Combines the entries of two arrays using a custom function

var array = [0, 1, 2, 3, 4];
var array2 = ["zero", "one", "two", "three"];

//["0 zero", "1 one", "2 two", "3 three"]
array.Zip(array2, "(x, y) => x + ' ' + y");

Reverse

Reverses the array

var array = ["item1", "item2", "item3", "item4", "no"];

//["no", "item4", "item3", "item2", "item1"]
array.Reverse();

Average

Computes the average of the elements

var array = [{val: 5}, {val: 3}, {val: 1}];

//3
array.Average("x => x.val");

//4
array.Average("x => x.val", "x => x.val > 1");


var array2 = [3, 4, 5];

//4
array2.Average();

Sum

Computes the sum of the elements

var array = [{val: 5}, {val: 3}, {val: 1}];

//9
array.Sum("x => x.val");

//8
array.Sum("x => x.val", "x => x.val > 1");


var array2 = [3, 4, 5];

//12
array2.Sum();

First

Returns the first item of the array and if a filter was set the first item that matches the filter - Throws an exception if no item was found

var array = ["no", "item1", "item2", "item3", "item4", "no"];

//"no"
array.First();

//"item1"
array.First("i => i.match(/item/gi)");

//Exception
array.First("i => i == 'notgiven'");

FirstOrDefault

Returns the first item of the array and if a filter was set the first item that matches the filter - returns null if no suitable item was found

var array = ["no", "item1", "item2", "item3", "item4", "no"];

//"no"
array.FirstOrDefault();

//"item1"
array.FirstOrDefault("i => i.match(/item/gi)");

//null
array.First("i => i == 'notgiven'");

Single

Returns the only item of the array - Throws an exception if not exactly one item is in array

var array = ["item1"];

//"item1"
array.Single();

var array = ["item1", "item2"];

//"item1"
array.Single("x => x == 'item1'");

//Exception
array.Single();

SingleOrDefault

Returns the only item of the array - Throws an exception if not only one item is in array

var array = ["item1"];

//"item1"
array.Single();

var array = ["item1", "item2"];

//"item1"
array.Single("x => x == 'item1'");

//Exception
array.Single();

//null
array.Single("x => x == 'item3'");

Min

Returns the smallest element in array

var array = [0, 8, 1, 5, -3];

//-3
array.Min();

var array = [{name: "test", age: 3}, {name: "test2", age: 18}];

//{name: "test", age: 3}
array.Min("x => x.age");

Last

Returns the last item of the array and if a filter was set the last item that matches the filter - Throws an exception if no item was found

var array = ["no", "item1", "item2", "item3", "item4", "no"];

//"no"
array.Last();

//"item4"
array.Last("i => i.match(/item/gi)");

//Exception
array.Last("i => i == 'notgiven'");

LastOrDefault

Returns the last item of the array and if a filter was set the last item that matches the filter - returns null if no suitable item was found

var array = ["no", "item1", "item2", "item3", "item4", "no"];

//"no"
array.LastOrDefault();

//"item4"
array.LastOrDefault("i => i.match(/item/gi)");

//null
array.LastOrDefault("i => i == 'notgiven'");

Max

Returns the greates element in array

var array = [0, 8, 1, 5, -3];

//8
array.Max();

var array = [{name: "test", age: 3}, {name: "test2", age: 18}];

//{name: "test2", age: 18}
array.Max("x => x.age");

Select

Select the properties for a new array

var array = [{Id: 1, Value: "item1"}, {Id: 2, Value: "item2"}];
	
//["item1", "item2"]
array.Select("i => i.Value");

//[{Custom: 1, Name: "item1"}, {Custom: 2, Name: "item2"}];
array.Select("i => {Custom: i.Id, Name: i.Value}");

When using the string syntax it is also possible to assign objects by the following methods

var array = [{Id: 1, Value: "item1"}, {Id: 2, Value: "item2"}];
	
//[{Value: item1}, {Value: item2}]
array.Select("i => {i.Value}");

//[{C: item1}, {C: item2}]
array.Select("i => {C: i.Value}");

//[{C: item1}, {C: item2}]
array.Select("i => {C = i.Value}");

SelectMany

Select the properties with an array as value and concats them

var array = [["item1", "item2"], ["item1", "item2"]];
	
//["item1", "item2", "item1", "item2"]
array.SelectMany("i => i");

Take

Limits the number of entries taken

var array = ["item1", "item2", "item3", "item4"];

//["item1", "item2"]
array.Take(2);

TakeWhile

Takes entries as long as a condition is true

var array = ["item1", "item2", "item3", "item2", "item4"];
var item2count = 0;

//["item1", "item2", "item3"]
array.TakeWhile(function(x){
	if(x == "item2"){
		item2count++;
	}

	return item2count < 2;
});

This is the basic usage. But if you want conditional executes for e.g. with counting this can get a little bit messy.

var array = ["item1", "item2", "item3", "item2", "item4"];

//["item1", "item2", "item3"]
array.TakeWhile(function(item, storage){
	return item != "item2" || storage.count < 1; //Condition
}, function(storage){
	storage.count = 0; //Init the Storage
}, function(item, storage){
	if(item == "item2"){
		storage.count++; //After executing the condition
	}
});

Skip

Skips entries

var array = ["item1", "item2", "item3", "item4"];

//["item3", "item4"]
array.Skip(2);

GroupBy

Groups array by property

var array = [
	{name: "Max", age: 17},
	{name: "Emily", age: 54},
	{name: "max", age: 32},
	{name: "emily", age: 12}
];

//[
//	[{name: "Emily", age: 54},{name: "emily", age: 12}],
//	[{name: "Max", age: 17},{name: "max", age: 32}]
//]
array.GroupBy("i => i.name.toLowerCase()");

OrderBy & OrderByDescending

Orders array by property or value

var array = ["item3", "item1", "item2", "item4"];
	
//["item4", "item3", "item2", "item1"]
array.OrderByDescending("i => i");
	
//["item1", "item2", "item3", "item4"]
array.OrderBy("i => i");

Also supports complex properties

var array = [
	{Name: "Max", Lastname: "Mustermann"},
	{Name: "John", Lastname: "Doe"},
	{Name: "Erika", Lastname: "Mustermann"}
];
	
//[{Name: "Max", Lastname: "Mustermann"},
//{Name: "Erika", Lastname: "Mustermann"},
//{Name: "John", Lastname: "Doe"}]
array.OrderByDescending("i => i.Lastname");

//[{Name: "John", Lastname: "Doe"}, 
//{Name: "Max", Lastname: "Mustermann"},
//{Name: "Erika", Lastname: "Mustermann"}]
array.OrderBy("i => i.Lastname");

ThenBy & ThenByDescending

Orders array by additional properties in combination with OrderBy/OrderByDescending

var array = [
	{Name: "Max", Lastname: "Mustermann"},
	{Name: "John", Lastname: "Doe"},
	{Name: "Erika", Lastname: "Mustermann"}
];
	
//[{Name: "Erika", Lastname: "Mustermann"},
//{Name: "Max", Lastname: "Mustermann"},
//{Name: "John", Lastname: "Doe"}]
array.OrderByDescending("i => i.Lastname").ThenBy("i => i.Name");

Move

Moves an item from one index to another

var array = ["item1", "item2", "item3", "item4"];

//["item1", "item3", "item4", "item2"]
array.Move(1, 3);

Distinct

Makes all values unique using the specified selector

var array = ["item1", "item2", "item2", "item3", "item4"];

//["item1", "item2", "item3", "item4"]
array.Distinct("x => x");
array.Distinct();

Evaluate

Evaluates SQL-String for array

var array = [...];

array.Evaluate("...");

Example SQL-string

clone
reverse
where x => x.Age > 70
order by x => x.Name
then by x => x.FirstName descending
for each x => console.log(x)
select x => {x.Name}

Supported methods (the methodname and aliases are not case-sensitive)

Methodname	Alias	Examples
Clone		clone
Reverse		reverse
Contains		contains 5
Join		join 5
Sum		sum
Average		average
Where		where x => x.Id > 3
Select		select x => x.Id
SelectMany	select many select ... many	select many x => x.Pets
Get		get 4
ForEach	for each	for each x => console.log(x)
Count		count x => x.Id
All		all x => x.Age > 4
Any		any x => x.Age > 4
Take		take 3
TakeWhile	take while take ... while	take while x => x.Age > 10
Skip		skip 3
Min		min x => x.Age
Max		max x => x.Age
GroupBy	group by	group by x => x.Name
Distinct		distinct x => x.Id
FindLastIndex	find last index find index ... last findindex ... last	find index x => x.Age == 3 last
FindIndex	find index find first index findfirstindex find index ... first findindex ... first	find index x => x.Age == 3 first
OrderByDescending	order by ... descending orderby ... descending orderby descending order by descending orderbydescending	order by x => x.Age descending
OrderBy	order by ... ascending orderby ... ascending orderby ascending order by ascending orderbyascending order by orderby	order by x => x.Age ascending
FirstOrDefault	first or default	first or default
LastOrDefault	last or default	last or default
SingleOrDefault	single or default	single or default
First		first
Last		last
Single		single
ThenByDescending	thenby ... descending then by ... descending thenbydescending then by descending	then by x => x.Name descending
ThenBy	thenby ... ascending then by ... ascending thenbyascending then byascending thenby then by	then by x => x.Name ascending

Author

Morris Janatzek (morrisjdev)