# Class: Collection\ Defined in: [collection.ts:7](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L7) ## Type Parameters ### Type `Type` ## Constructors ### Constructor ```ts new Collection(items?: Type[]): Collection; ``` Defined in: [collection.ts:10](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L10) #### Parameters ##### items? `Type`[] #### Returns `Collection`\<`Type`\> ## Methods ### add() ```ts add(data: Type): this; ``` Defined in: [collection.ts:38](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L38) Adds a new element to the end of the collection #### Parameters ##### data `Type` #### Returns `this` *** ### all() ```ts all(): Type[]; ``` Defined in: [collection.ts:205](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L205) Returns the underlying array represented by the collection #### Returns `Type`[] *** ### clone() ```ts clone(): Collection; ``` Defined in: [collection.ts:198](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L198) Creates a shallow copy of collection #### Returns `Collection`\<`Type`\> *** ### concat() ```ts concat(collection: Collection): this; ``` Defined in: [collection.ts:128](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L128) Combines elements from both collections into one #### Parameters ##### collection `Collection`\<`Type`\> #### Returns `this` *** ### count() ```ts count(): number; ``` Defined in: [collection.ts:78](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L78) Returns the number of items in the collection #### Returns `number` *** ### filter() ```ts filter(iterator: CollectionIterator): Collection; ``` Defined in: [collection.ts:107](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L107) Iterates over elements of collection, returning a collection of all elements that meets the requirements #### Parameters ##### iterator [`CollectionIterator`](../type-aliases/CollectionIterator.md) #### Returns `Collection`\<`Type`\> *** ### find() ```ts find(iterator: CollectionIterator): Type; ``` Defined in: [collection.ts:33](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L33) Return the first element of the collection that meets the requirements #### Parameters ##### iterator [`CollectionIterator`](../type-aliases/CollectionIterator.md) #### Returns `Type` *** ### first() ```ts first(iterator?: CollectionIterator): Type; ``` Defined in: [collection.ts:15](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L15) Gets the first element of collection #### Parameters ##### iterator? [`CollectionIterator`](../type-aliases/CollectionIterator.md) #### Returns `Type` *** ### forEach() ```ts forEach(callback: (item: Type, index?: number) => void | Promise): this; ``` Defined in: [collection.ts:114](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L114) Iterates over elements of collection and invokes callback for each element #### Parameters ##### callback (`item`: `Type`, `index?`: `number`) => `void` \| `Promise`\<`void`\> #### Returns `this` *** ### groupBy() ```ts groupBy(iterator: CollectionIterator): Dictionary; ``` Defined in: [collection.ts:184](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L184) Creates a Dictionary composed of keys generated from the results of running each element of collection thru iterator #### Parameters ##### iterator [`CollectionIterator`](../type-aliases/CollectionIterator.md) #### Returns [`Dictionary`](Dictionary.md)\<`Type`[]\> *** ### includes() ```ts includes(value: CollectionIterator): boolean; ``` Defined in: [collection.ts:167](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L167) Checks if value is in collection #### Parameters ##### value [`CollectionIterator`](../type-aliases/CollectionIterator.md) #### Returns `boolean` *** ### indexOf() ```ts indexOf(item: Type): number; ``` Defined in: [collection.ts:88](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L88) Gets the index at which the first occurrence of value is found in collection #### Parameters ##### item `Type` #### Returns `number` *** ### intersects() ```ts intersects(collection: Collection): Collection; ``` Defined in: [collection.ts:50](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L50) Returns a new collection with all unique elements that are in both collections #### Parameters ##### collection `Collection`\<`Type`\> #### Returns `Collection`\<`Type`\> *** ### intersectsBy() ```ts intersectsBy(collection: Collection, iterator: string | CollectionIterator): Collection; ``` Defined in: [collection.ts:59](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L59) Returns a new collection with all unique elements that are in both collections, taking into account the specified requirements #### Parameters ##### collection `Collection`\<`Type`\> ##### iterator `string` | [`CollectionIterator`](../type-aliases/CollectionIterator.md) #### Returns `Collection`\<`Type`\> *** ### isEmpty() ```ts isEmpty(): boolean; ``` Defined in: [collection.ts:137](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L137) Returns `true` if the collection is empty #### Returns `boolean` *** ### isNotEmpty() ```ts isNotEmpty(): boolean; ``` Defined in: [collection.ts:142](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L142) Returns `true` if the collection is not empty #### Returns `boolean` *** ### join() ```ts join(separator: string): string; ``` Defined in: [collection.ts:83](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L83) Converts all elements in collection into a string separated by separator #### Parameters ##### separator `string` #### Returns `string` *** ### keyBy() ```ts keyBy(iterator: CollectionIterator): Dictionary; ``` Defined in: [collection.ts:177](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L177) Creates a Dictionary composed of keys generated from the results of running each element of collection thru iterator #### Parameters ##### iterator [`CollectionIterator`](../type-aliases/CollectionIterator.md) #### Returns [`Dictionary`](Dictionary.md)\<`Type`\> *** ### last() ```ts last(predicate?: CollectionIterator): Type; ``` Defined in: [collection.ts:24](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L24) Gets the last element of collection #### Parameters ##### predicate? [`CollectionIterator`](../type-aliases/CollectionIterator.md) #### Returns `Type` *** ### map() ```ts map(iterator: (item: any) => Type): Collection; ``` Defined in: [collection.ts:191](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L191) Creates a new Collection of values by running each element in collection thru iterator #### Type Parameters ##### Type `Type` #### Parameters ##### iterator (`item`: `any`) => `Type` #### Returns `Collection`\<`Type`\> *** ### missing() ```ts missing(value: CollectionIterator): boolean; ``` Defined in: [collection.ts:172](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L172) Checks whether a value is missing from the collection #### Parameters ##### value [`CollectionIterator`](../type-aliases/CollectionIterator.md) #### Returns `boolean` *** ### remove() ```ts remove(iterator: CollectionIterator): Collection; ``` Defined in: [collection.ts:121](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L121) Removes all elements from collection that meets the requirements #### Parameters ##### iterator [`CollectionIterator`](../type-aliases/CollectionIterator.md) #### Returns `Collection`\<`Type`\> *** ### sample() ```ts sample(): Type; ``` Defined in: [collection.ts:45](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L45) Gets a random element from collection #### Returns `Type` *** ### slice() ```ts slice(start?: number, end?: number): Collection; ``` Defined in: [collection.ts:71](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L71) Creates a slice of collection from start up to, but not including, end #### Parameters ##### start? `number` ##### end? `number` #### Returns `Collection`\<`Type`\> *** ### sort() ```ts sort(): Collection; ``` Defined in: [collection.ts:147](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L147) Sorts the items in the collection alphabetically #### Returns `Collection`\<`Type`\> *** ### sortBy() ```ts sortBy( iterators: | CollectionIterator | CollectionIterator[], orders: string[] | "desc" | "asc", natural: boolean): this; ``` Defined in: [collection.ts:154](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L154) Sorts collection items according to requirements #### Parameters ##### iterators [`CollectionIterator`](../type-aliases/CollectionIterator.md) | [`CollectionIterator`](../type-aliases/CollectionIterator.md)[] ##### orders `string`[] | `"desc"` | `"asc"` ##### natural `boolean` = `true` #### Returns `this` *** ### toJSON() ```ts toJSON(): string; ``` Defined in: [collection.ts:210](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L210) Converts the collection into a JSON serialized string #### Returns `string` *** ### uniq() ```ts uniq(): Collection; ``` Defined in: [collection.ts:93](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L93) Creates a duplicate-free version of a collection #### Returns `Collection`\<`Type`\> *** ### uniqBy() ```ts uniqBy(iterator: CollectionIterator): Collection; ``` Defined in: [collection.ts:100](https://github.com/freearhey/core-js/blob/master/src/collection.ts#L100) Creates a duplicate-free version of a collection according to requirements #### Parameters ##### iterator [`CollectionIterator`](../type-aliases/CollectionIterator.md) #### Returns `Collection`\<`Type`\>