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@angular/corecode
QueryList
Class
stable
An unmodifiable list of items that Angular keeps up to date when the state of the application changes.
Using QueryListOn this page
API
class QueryList<T> implements Iterable<T> { constructor(_emitDistinctChangesOnly?: boolean); readonly dirty: true; readonly length: number; readonly first: T; readonly last: T; readonly changes: Observable<any>; get(index: number): T | undefined; map<U>(fn: (item: T, index: number, array: T[]) => U): U[]; filter<S extends T>(predicate: (value: T, index: number, array: readonly T[]) => value is S): S[]; filter(predicate: (value: T, index: number, array: readonly T[]) => unknown): 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) | undefined): void; notifyOnChanges(): void; setDirty(): void; destroy(): void; [Symbol.iterator]: () => Iterator<T, any, any>;}
dirty
truelength
numberlast
Tfilter
2 overloadsSee Array.filter
@parampredicate
(value: T, index: number, array: readonly T[]) => value is S@returns
S[]@parampredicate
(value: T, index: number, array: readonly T[]) => unknown@returns
T[]reduce
USee Array.reduce
@paramfn
(prevValue: U, curValue: T, curIndex: number, array: T[]) => U@paraminit
U@returns
Ureset
voidUpdates 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) | undefinedOptional 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).
@returns
void[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>;
}Jump to details