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QueryList
class
final
An unmodifiable list of items that Angular keeps up to date when the state of the application changes.
class QueryList<T> implements Iterable<T> {
constructor(_emitDistinctChangesOnly: boolean = false)
dirty: true
length: number
first: T
last: T
changes: Observable<any>
get(index: number): T | undefined
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(resultsTree: (any[] | T)[], identityAccessor?: (value: T) => unknown): 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.
Further information is available in the Usage Notes...
Constructor
|
_emitDistinctChangesOnly |
boolean |
Optional. Default is |
Properties
Property | Description |
---|---|
dirty: true |
Read-Only |
length: number |
Read-Only |
first: T |
Read-Only |
last: T |
Read-Only |
changes: Observable<any> |
Read-Only Returns |
Methods
get()
|
|||
---|---|---|---|
Returns the QueryList entry at |
|||
|
index |
number |
Returns
T | undefined
map()
|
|||
---|---|---|---|
See Array.map |
|||
|
fn |
(item: T, index: number, array: T[]) => U |
Returns
U[]
filter()
|
|||
---|---|---|---|
See Array.filter |
|||
|
fn |
(item: T, index: number, array: T[]) => boolean |
Returns
T[]
find()
|
|||
---|---|---|---|
See Array.find |
|||
|
fn |
(item: T, index: number, array: T[]) => boolean |
Returns
T | undefined
reduce()
|
||||||
---|---|---|---|---|---|---|
See Array.reduce |
||||||
|
fn |
(prevValue: U, curValue: T, curIndex: number, array: T[]) => U |
|
init |
U |
Returns
U
forEach()
|
|||
---|---|---|---|
See Array.forEach |
|||
|
fn |
(item: T, index: number, array: T[]) => void |
Returns
void
some()
|
|||
---|---|---|---|
See Array.some |
|||
|
fn |
(value: T, index: number, array: T[]) => boolean |
Returns
boolean
toArray()
|
---|
Returns a copy of the internal results list as an Array. |
|
toString()
|
---|
|
reset()
|
||||||
---|---|---|---|---|---|---|
Updates the stored data of the query list, and resets the |
||||||
|
resultsTree |
(any[] | T)[] |
The query results to store |
identityAccessor |
(value: T) => unknown |
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 Optional. Default is |
Returns
void
notifyOnChanges()
|
---|
Triggers a change event by emitting on the |
|
setDirty()
|
---|
internal |
|
destroy()
|
---|
internal |
|
Usage notes
Example
@Component({...})
class Container {
@ViewChildren(Item) items:QueryList<Item>;
}
© 2010–2022 Google, Inc.
Licensed under the Creative Commons Attribution License 4.0.
https://v13.angular.io/api/core/QueryList