linqjs

JavaScript linq methods

Methods

Name	Parameters	Return	Description
Array.lambda	(predicate: string*)	function	Converts linq string expression into JavaScript function. For example "x=>x.value" would be converted to function (x) { return x.value; }.
forEach	(predicate: function*)	void	https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach
first	(predicate: function)	object	Returns first matching element.
last	(predicate: function)	object	Returns last matching element.
where	(predicate: function*)	array	Returns new array with matching elements.
select	(predicate: function*)	array	Returns new array with returned values per each element.
selectMany	(predicate: function*)	array	Returns new array which contains all of the elements of returned arrays per each element.
take	(n: integer*)	array	Returns new array with N first elements of the original array.
skip	(n: integer*)	array	Returns new array without N first elements of the original array.
clear		void	Removes all of the array elements.
contains	(element: object*)	boolean	Returns true if provided element is within array, false otherwise.
group	(predicate: function*)	array	Groups array items by value, returns array of groups, where each groups is an array of element with key property.
sum	(predicate: function, defaultValue: object)	number/string	Returns sum of all selected values or default value if no elements in array.
max	(predicate: function, defaultValue: object)	number/string	Returns max value of all selected values or default value if no elements in array.
min	(predicate: function, defaultValue: object)	number/string	Returns min value of all selected values or default value if no elements in array.
avg	(predicate: function, defaultValue: object)	number/string	Returns average value of all selected values or default value if no elements in array.
distinct	(predicate: function)	array	Returns new array with unique elements from the original array.
copy		array	Returns a copy of the original array, same as array.slice().
any	(predicate: function)	boolean	Returns true if an element was found in the array, false otherwise.
orderBy	(predicate: function*, desc: boolen)	array	Returns new array with elements from the original array sorted by value provided.
orderByDesc	(predicate: function*)	array	Same as array.orderBy(expression, true);
findIndex	(predicate: function*)	integer	Returns index of matching element, -1 if no elements match the predicate.
removeElement	(element: object*)	void	Removes element from array.
removeAt	(index: integer*)	void	Removes element at position index, equals to array.splice(index, 1).

• The parameters marked with * are required.
• The predicate function may be passed as a function or as a string which will be converted to a function with Array.lambda method.

Examples

The following array will be used in all examples:

var array = [{ value: 0 }, { value: 1 }, { value: 2 }, { value: 3 }, { value: 4 }, { value: 5 }, { value: 6 }, { value: 7 }, { value: 8 }, { value: 9 }];

first

console.log(array.first("x => x.value > 1"));

{ value: 2 }

last

console.log(array.last("x => x.value > 1"));

{ value: 9 }

where

console.log(array.where("x => x.value % 2 == 0"));

[{ value: 0 }, { value: 2 }, { value: 4 }, { value: 6 }, { value: 8 }]

select

console.log(array.select("x => x.value"));

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

selectMany

console.log(array.selectMany(function(item, index) {
	return [item.value, item.value];
}));

[0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9];

take

console.log(array.take(2));

[{ value: 0 }, { value: 1 }]

skip

console.log(array.skip(8));

[{ value: 8 }, { value: 9 }]

contains

console.log([1, 2, 3].contains(2));
console.log([1, 2, 3].contains(5));

true
false

group

var b = array.group("x => x.value % 2");

console.log(b);
console.log(b.select("x => x.key"));

[
	[{ value: 0 }, { value: 2 }, { value: 4 }, { value: 6 }, { value: 8 }], 
	[{ value: 1 }, { value: 3 }, { value: 5 }, { value: 7 }, { value: 9 }]
]

[0, 1]

sum

console.log(array.sum("x => x.value"));

45

max

console.log(array.max("x => x.value"));

9

min

console.log(array.min("x => x.value"));

0

avg

console.log(array.avg("x => x.value"));

4.5

distinct

console.log([1, 2, 1, 3, 3, 4, 5].distinct("x => x"));

[1, 2, 3, 4, 5]

#### any

```js
console.log([1, 2, 3].any("x => x == 2"));
console.log([1, 2, 3].any("x => x == 5"));

true
false

orderBy

console.log([1, 2, 1, 3, 3, 4, 5].orderBy("x => x"));

[1, 1, 2, 3, 3, 4, 5]

orderByDesc

console.log([1, 2, 1, 3, 3, 4, 5].orderBy("x => x"));

[5, 4, 3, 3, 2, 1, 1]

findIndex

console.log(array.findIndex("x => x.value == 2"));
console.log(array.findIndex("x => x.value == 10"));

2
-1