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Questions tagged [angular2-changedetection]

473 questions
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Angular 2 OnPush change detection for dynamic components

I have an Angular component that dynamically creates various other types of component inside itself. It binds its own properties to child component @Input properties via an OnChanges hook. This binding works fine when the child component's change…
Chris Fulstow
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Angular2 manually implement change detection using ApplicationRef

Getting a change detection error Expression has changed after it was checked. Previous value: 'true'. Current value: 'false' so I want to manually run another round of change detection. Found information about using ApplicationRef.tick() but…
Drew13
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Showing Validation messages with Reactive Forms and ChangeDetectionStrategy.OnPush

I'm trying to migrate an app to using ChangeDetectionStrategy.OnPush. However, I'm running into a bit of a blocker trying to work with some reactive forms. I've got a reusable control that shows validation messages based on some of the state flags…
Daniel Schaffer
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What is the performance impact for a class / interface with a lot of fields?

I have a class (interface) in my angular 4 app which has a lot of fields. Note that the instance of this class/interface is immutable (i.e. the members will NEVER be changed). E.g. public interface IHaveALotOfFields { field1: string; //... …
OschtärEi
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Angular2 change detection misunderstanding - With plunker

I'm trying to fully understand change detection with Angular2 final. This include: Dealing with change detection strategies Attaching and detaching change detector from a component. I thought I already got a pretty clear overview of those…
Clement
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Angular Change detection not working with ChangeDetectionStrategy.OnPush in HttpClinet.Subscribe

I have reproduced a simple stackblitz demonstrating the issue I have been having. The problem is that I have a parent component that passes a boolean to a child component. This boolean is an @Input on the child component. It is important to note…
Pat
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Angular NgZone.runOutsideAngular and OnPush change detection strategy

I'm trying to optimize the performance of code in angular application. I know that I can runOutsideAngular some code in order not to cause change detection on each code run or event. However, do I need to use runOutsideAngular when I utilize OnPush…
Sergey
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How to detect change from one component into other

Angular 4. Github source I have a menu which is filled by a web service. The web service is in taskService, but is not necessary now. ngOnInit() { this.getTasks(); } getTasks(): void { this.taskService.getTasks() …
ValRob
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Angular - Input data not immediately available on child component, why?

I have a child Calendar Component that receives events from his father through an input field. @Input() private events: any[]; When the month changes the parent gets new events from an API Service and calls the child component to show them. private…
Willa
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Angular 4 + Jasmine Unit Tests: Reasons why fixture.detectChanges() may not work upon change of @Input() variables

Been running into this one issue and scouring the internet about fixture.detectChanges() where it does not recognize changes in @Input() when explicitly inserting mock data. There are tons of threads and docs that describe the setup but not…
Eric
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Angular 2 Change Detection Breaks Down with Electron

I have an Electron app using Angular 2. The app works fine until a load data from a local JSON file using ipcRenderer. Then buttons which act on data in a service no longer trigger change detection process to update the view. I created a simplified…
Marshmellow1328
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angular 2 subscribe value change not reflecting on html

This is quite confusing to me. I might not have a solid understanding of how subscription works. Angular 2 finalized version Goal: Hide/Show navigation menu based on roles Approach: I use Facebook to authenticate users. After authentication, user…
Chuck
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Angular2: Watch an external variable outside of angular

I want to be able to watch and update when a variable outside of angular2 changes. So let's say I have this in an external javascript file: var test = 1; How can I bind this variable to a property in a component? @Component({ ... }) export…
Sebastian Olsen
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Change component input from ngOnChanges, while using OnPush strategy

I'm having a problem with an Angular 6 application: The problem Let's say I have 2 components: parent and child. the child has 2 inputs. While 1 input changes, inside the ngOnChanges() the child component emit somthing to the parent component. Then…
Naor Talmor
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Is it normal for Angular to re-render infinitely even when no changes are made?

The question Is Angular designed to constantly re-check everything in order to detect changes? I'm coming from the React world and I was expect something like event triggered -> re-rendering. I don't know if this is something from my app or…
Raul Rene
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