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API > @angular/core

QueryList

An unmodifiable list of items that Angular keeps up to date when the state of the application changes.

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      class QueryList<T> {
  dirty: true
  changes: Observable<any>
  length: number
  first: T
  last: T
  map<U>(fn: (item: T, index: number, array: T[]) => U): U[]
  filter(fn: (item: T, index: number, array: T[]) => boolean): T[]
  find(fn: (item: T, index: number, array: T[]) => boolean): T | undefined
  reduce<U>(fn: (prevValue: U, curValue: T, curIndex: number, array: T[]) => U, init: U): U
  forEach(fn: (item: T, index: number, array: T[]) => void): void
  some(fn: (value: T, index: number, array: T[]) => boolean): boolean
  toArray(): T[]
  toString(): string
  reset(res: Array<T | any[]>): void
  notifyOnChanges(): void
  setDirty()
  destroy(): void
}

Description

The type of object that ViewChildren, ContentChildren, and QueryList provide.

Implements an iterable interface, therefore it can be used in both ES6 javascript for (var i of items) loops as well as in Angular templates with *ngFor="let i of myList".

Changes can be observed by subscribing to the changes Observable.

NOTE: In the future this class will implement an Observable interface.

Properties

Property Description
dirty: true Read-only.
changes: Observable<any> Read-only.
length: number Read-only.
first: T Read-only.
last: T Read-only.

Methods

map()

See Array.map
map<U>(fn: (item: T, index: number, array: T[]) => U): U[]
      
      map<U>(fn: (item: T, index: number, array: T[]) => U): U[]

Parameters

fn

Type: (item: T, index: number, array: T[]) => U.

Returns

U[]

filter()

See Array.filter
filter(fn: (item: T, index: number, array: T[]) => boolean): T[]
      
      filter(fn: (item: T, index: number, array: T[]) => boolean): T[]

Parameters

fn

Type: (item: T, index: number, array: T[]) => boolean.

Returns

T[]

find()

See Array.find
find(fn: (item: T, index: number, array: T[]) => boolean): T | undefined
      
      find(fn: (item: T, index: number, array: T[]) => boolean): T | undefined

Parameters

fn

Type: (item: T, index: number, array: T[]) => boolean.

Returns

T | undefined

reduce()

See Array.reduce
reduce<U>(fn: (prevValue: U, curValue: T, curIndex: number, array: T[]) => U, init: U): U
      
      reduce<U>(fn: (prevValue: U, curValue: T, curIndex: number, array: T[]) => U, init: U): U

Parameters

fn

Type: (prevValue: U, curValue: T, curIndex: number, array: T[]) => U.
init

Type: U.

Returns

U

forEach()

See Array.forEach
forEach(fn: (item: T, index: number, array: T[]) => void): void
      
      forEach(fn: (item: T, index: number, array: T[]) => void): void

Parameters

fn

Type: (item: T, index: number, array: T[]) => void.

Returns

void

some()

See Array.some
some(fn: (value: T, index: number, array: T[]) => boolean): boolean
      
      some(fn: (value: T, index: number, array: T[]) => boolean): boolean

Parameters

fn

Type: (value: T, index: number, array: T[]) => boolean.

Returns

boolean

toArray()

toArray(): T[]
      
      toArray(): T[]

Parameters

There are no parameters.

Returns

T[]

toString()

toString(): string
      
      toString(): string

Parameters

There are no parameters.

Returns

string

reset()

reset(res: Array<T | any[]>): void
      
      reset(res: Array<T | any[]>): void

Parameters

res

Type: Array.

Returns

void

notifyOnChanges()

notifyOnChanges(): void
      
      notifyOnChanges(): void

Parameters

There are no parameters.

Returns

void

setDirty()

internal
setDirty()
      
      setDirty()

Parameters

There are no parameters.

destroy()

internal
destroy(): void
      
      destroy(): void

Parameters

There are no parameters.

Returns

void

Usage notes

Example

@Component({...}) class Container { @ViewChildren(Item) items:QueryList<Item>; } 
      
      @Component({...})
class Container {
  @ViewChildren(Item) items:QueryList<Item>;
}