@angular/core

QueryList

Class

stable

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

API

  
    class QueryList<T> implements Iterable<T> {
}

constructor

QueryList<T>

@param_emitDistinctChangesOnlyboolean

@returnsQueryList<T>

dirty

true

length

number

first

T

last

T

changes

Observable<any>

Returns Observable of QueryList notifying the subscriber of changes.

get

T | undefined

Returns the QueryList entry at index.

@paramindexnumber

@returnsT | undefined

map

U[]

See Array.map

@paramfn(item: T, index: number, array: T[]) => U

@returnsU[]

filter

2 overloads

See Array.filter

@parampredicate(value: T, index: number, array: readonly T[]) => value is S

@returnsS[]

@parampredicate(value: T, index: number, array: readonly T[]) => unknown

@returnsT[]

find

T | undefined

See Array.find

@paramfn(item: T, index: number, array: T[]) => boolean

@returnsT | undefined

reduce

U

See Array.reduce

@paramfn(prevValue: U, curValue: T, curIndex: number, array: T[]) => U

@paraminitU

@returnsU

forEach

void

See Array.forEach

@paramfn(item: T, index: number, array: T[]) => void

@returnsvoid

some

boolean

See Array.some

@paramfn(value: T, index: number, array: T[]) => boolean

@returnsboolean

toArray

T[]

Returns a copy of the internal results list as an Array.

@returnsT[]

toString

string

@returnsstring

reset

void

Updates the stored data of the query list, and resets the dirty flag to false, so that on change detection, it will not notify of changes to the queries, unless a new change occurs.

@paramresultsTree(any[] | T)[]

The query results to store

@paramidentityAccessor((value: T) => unknown) | undefined

Optional function for extracting stable object identity from a value in the array. This function is executed for each element of the query result list while comparing current query list with the new one (provided as a first argument of the reset function) to detect if the lists are different. If the function is not provided, elements are compared as is (without any pre-processing).

@returnsvoid

notifyOnChanges

void

Triggers a change event by emitting on the changes EventEmitter.

@returnsvoid

setDirty

void

internal

@returnsvoid

destroy

void

internal

@returnsvoid

[Symbol.iterator]

() => Iterator<T, any, any>

Description

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

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 @for(i of myList; track $index).

Changes can be observed by subscribing to the changes Observable. *

Usage Notes

Example

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