QueryList
class
An unmodifiable list of items that Angular keeps up to date when the state of the application changes.
class QueryList<T> implements Iterable {
constructor(_emitDistinctChangesOnly: boolean = false)
dirty: true
length: number
first: T
last: T
changes: Observable<any>
__@iterator: () => Iterator<T>
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 available in the Usage Notes...
Constructor
constructor(_emitDistinctChangesOnly: boolean = false)Parameters
|
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 |
__@iterator: () => Iterator<T>
|
Methods
get() | |||
---|---|---|---|
Returns the QueryList entry at index .
| |||
get(index: number): T | undefinedParameters
Returns
|
map() | |||
---|---|---|---|
See Array.map | |||
map<U>(fn: (item: T, index: number, array: T[]) => U): U[]Parameters
Returns
|
filter() | |||
---|---|---|---|
See Array.filter | |||
filter(fn: (item: T, index: number, array: T[]) => boolean): T[]Parameters
Returns
|
find() | |||
---|---|---|---|
See Array.find | |||
find(fn: (item: T, index: number, array: T[]) => boolean): T | undefinedParameters
Returns
|
reduce() | ||||||
---|---|---|---|---|---|---|
See Array.reduce | ||||||
reduce<U>(fn: (prevValue: U, curValue: T, curIndex: number, array: T[]) => U, init: U): UParameters
Returns
|
forEach() | |||
---|---|---|---|
See Array.forEach | |||
forEach(fn: (item: T, index: number, array: T[]) => void): voidParameters
Returns
|
some() | |||
---|---|---|---|
See Array.some | |||
some(fn: (value: T, index: number, array: T[]) => boolean): booleanParameters
Returns
|
toArray() |
---|
Returns a copy of the internal results list as an Array. |
toArray(): T[]ParametersThere are no parameters. Returns
|
toString() |
---|
toString(): stringParametersThere are no parameters. Returns
|
reset() | ||||||
---|---|---|---|---|---|---|
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.
| ||||||
reset(resultsTree: (any[] | T)[], identityAccessor?: (value: T) => unknown): voidParameters
Returns
|
notifyOnChanges() |
---|
Triggers a change event by emitting on the changes EventEmitter.
|
notifyOnChanges(): voidParametersThere are no parameters. Returns
|
setDirty() |
---|
internal |
setDirty()ParametersThere are no parameters.
|
destroy() |
---|
internal |
destroy(): voidParametersThere are no parameters. Returns
|
Usage notes
Example
@Component({...})
class Container {
@ViewChildren(Item) items:QueryList<Item>;
}
© 2010–2021 Google, Inc.
Licensed under the Creative Commons Attribution License 4.0.
https://v11.angular.io/api/core/QueryList