What Zone.js can do
- Provide execution context between the async operation
- Provide async life cycle hooks
- Provide unified async Error handling mechanism
How does zone JS work?
In a Nutshell: How Does Zone.js Work? 1 Zone. Zone is a mechanism for intercepting and keeping track of asynchronous work. 2 Tasks. For each async operation, Zone.js creates a task. ... 3 NgZone. By default, in an Angular app every task runs in the “Angular” Zone, which is called NgZone. ... 4 Root Zone/Forks. ... 5 ZoneSpecs. ...
What does angular use zonejs for?
That sounds good, and apparently Angular simply uses zonejs for domains like errors, traces of stack, etc. However that's not all zone js do. It has more vital tasks underneath.
What happens during initialization in zone JS?
During initialization zone.js does the same process along with all the browser APIs. Let’s take the example of the setTimeout API. During initialization, zone.js creates a ZoneTask using setTimeout ’s parameter and schedules it in the current Zone (more on it later). This ZoneTask is an object which implements the Task interface.
What is the difference between targetzone and parentzonedelegate?
targetZone — It refers to the Zone in which the Task was invoked. task — It refers to the task that’s supposed to be executed. parentZoneDelegate — It’s a special object ZoneDelegate which maintains the reference to the parent Zone which defines the same hook for interception.
What is Zone ?
How does Zone help us?
What is a parent zone delegate?
What is currentzone in a task?
Does childazone intercept hellofunction?
See 2 more
About this website
javascript - How to use zone.js in Angular? - Stack Overflow
I would like to use zone.js in my Angular project ( not just the runOutsideAngularZone function ). I tried to include it like this: import { zone } from 'zone.js'; Unfortunately I get this error:
What the hell is Zone.js and why is it in my Angular 2?
Note: If you’re interested in a brief overview of zonejs and what it does, stay here. If you’re looking for a deeper dive, check out my series on how Angular2 works on a source code level here…
Is zone.js for Angular, what is the virtual DOM for React?
Pascal Precht wrote a great article on change detection in Angular. While I understand that zone.js and virtual DOM are completely different concepts, is zone.js for Angular the equivalent of virtu...
What is zone.js?
Zone.js is basically used to create new context and execute code within it.
Why do we add hooks to a zone?
While creating a Zone using “ fork ”, we can add Hooks to the Zone. Hooks can be used in order to track the execution and failure scenarios within a specified zone. Using these hooks you can maintain some global variables available to the executing Zone and well as provide Error Handling Capabilities.
When is onzonecreated executed?
onZoneCreated: Executed when the Zone is initially created
Can you fork a zone in Zone.js?
As soon as we add Zone.js to the application, we add a global “zone” object to the window. We can fork a new zone which inherits from the “parent” zone.
Can JavaScript execute asynchronously?
We can understand the given Hooks with some sample Code that contains Asynchronous Execution. Since we will be having Asynchronous Code, the execution of JavaScript will enter and exit the zone multiple times.
What is Zone.js
Every JavaScript Code that we execute, is executed within an Execution Context. Zone.js is a way of creating a new Context and getting the code executed within that context/Zone. Any code enclosed within a Zone whether synchronous or asynchronous is executed within the same context.
Why do we use Zone.js
In this section, we will analyze a problem statement that need to be resolved. In the code below, we have some synchronous functions that need to be executed, and we would like to evaluate the total time of Execution of these functions. Let’s look for the code to evaluate the same.
What is zone.js patch?
zone.js patches the async APIs described above, but those patches will have some overhead. Starting from zone.js v0.8.9, you can choose which web API module you want to patch. For more details, please see MODULE.md.
Does Zone Legacy include IE?
the bundle for evergreen browsers, doesn't include the patch for legacy browsers such as IE or old versions of Firefox/Safari. zone-legacy.js. the patch bundle for legacy browsers, only includes the patch for legacy browsers such as IE or old versions of Firefox/Safari.
Why is ZoneJS important?
So, ZoneJs acts as its replacement in Angular 2 and serves all the change detection purpose:
Is zone run the same as $digest?
So to sum up, zone.run () is similar to the new $digest ().
Does Angular use ZoneJS?
That sounds good, and apparently Angular simply uses zonejs for domains like errors, traces of stack, etc. However that's not all zone js do. It has more vital tasks underneath.
What is a zone.js?
Zone.js zones are hierarchical which means you always start with a top-level Zone — the “root” Zone. New Zones can be created by forking the root Zone. NgZone is also a fork of the root Zone.
Why is Zone.js used in Angular?
Angular introduced Zone.js to handle change detection. This allows Angular to decide when the UI has to be refreshed. Usually, you don’t have to care about any of this, because Zone.js just works.
What does it mean when a zone is stable?
A Zone is stable once no async operations are running anymore. A “healthy” Zone starts stable, then some tasks are run which means the Zone becomes “unstable” and, at some point, tasks complete which means the Zone becomes stable again.
What is TaskTrackingZoneSpec?
TaskTrackingZoneSpec: Can be used to track all current tasks and offers an API to inspect them.
What happens when you fork a zone?
When forking a Zone, a new Zone will be created based on a ZoneSpec. A ZoneSpec can just include a name for the new child Zone, or can include various Hook methods which can be used to intercept certain Zone/task events.
What are the different types of debugging zones?
When debugging Zones, you will see that there are different types of tasks: micro and macro. In general, it’s best to start looking at the macro tasks first, because most problems are related to macro tasks.
What is zone in asynchronous work?
Zone is a mechanism for intercepting and keeping track of asynchronous work.
What is a zone in JavaScript?
A zone is an execution context that persists across async tasks. You can think of it as thread-local storage for JavaScript VMs. This guide describes how to use Angular's NgZone to automatically detect changes in the component to update HTML.
How to make Zone.js available in Angular?
To make Zone.js available in Angular, you need to import the zone.js package. If you are using the Angular CLI, this step is done automatically, and you will see the following line in the src/polyfills.ts:
Why do we need zones in Angular?
Zone helps Angular know when to trigger change detection and let the developers focus on the application development. By default, Zone is loaded and works without additional configuration. However, you don't necessarily have to use Zone to make Angular work.
How to get context for zoneThis?
This new context, zoneThis, can be retrieved from the setTimeout () callback function, and this context is the same when the setTimeout () is scheduled. To get the context, you can call Zone.current.
What is Zone ?
A Zone is an execution context that persists across async tasks. In other words, all the async tasks such as setTimeout, Promise, XHRs etc. are executed in a particular context. In case of zone.js, all these async tasks are executed in a single context which is called Zone. But what is execution context ? Please do read this awesome article to understand about the “execution context”.
How does Zone help us?
Zone also provides us with the ability to create more child zones by exposing one of its API fork allowing us to create hierarchical structure in zones which would help us to have each zone with distinct responsibilities.
What is a parent zone delegate?
parentZoneDelegate — It’s a special object ZoneDelegate which maintains the reference to the parent Zone which defines the same hook for interception.
What is currentzone in a task?
currentZone — It refers to the Zone which is currently intercepting the task.
Does childazone intercept hellofunction?
So childAZone also intercepts this helloFunction and logs “intercepted in childAZone before execution”. childAZone also follows the same process and sends this function to the closest parent which also defines the interception for any function.
