In this video, Aviv Ben-Yosef explains how the $doCheck lifecycle hook works. Learn how it can be used to replace $scope.$watch calls in a safe manner.
- [Instructor] While on changes can be used…to replace some simple watch operations,…it can't replace all of them.…For that purpose,…the Do Check hook was introduced.…It's a hook that Angler executes…whenever it runs the digest cycle.…Since it gets culled so frequently,…it's a great place to regularly check if anything…has changed that requires the component's attention.…Do Check is useful for replacing non obvious watch calls,…like deep watches,…or watches on objects that are not bound.…
These cases should be low,…but when they do come up…Do Check can help…and it can be used to remove…another usage of scope along the way.…Let us inspect the to do component in to the jazz…in the exercise files.…As you can see, it still has a usage of watch…for displaying a message whenever the to do…is marked as done.…To change this, I start with adding…a Do Check method.…
The hook does not receive any arguments.…The next step is to do a check for changes…in the value of to do done.…That requires manually saving the previous value…and keeping track of it in order to compare it…
Aviv Ben-Yosef kicks off the course by explaining what's different in Angular 1.6, as well the different motives for upgrading. Next, he walks through how to safely upgrade an existing app. He covers going from controllers to directives, as well as component lifecycle hooks. He also goes into the architectural changes in Angular, such as one-way data flow and immutability. To wrap up, he discusses how to properly test components.
- Deciding to upgrade an existing app
- Upgrading to Angular 1.6
- Removing standalone controllers
- Using directives as route targets
- Converting a controller's code
- Converting a controller's template
- Comparing directives and components
- Converting a directive
- Reviewing the concept of one-way binding
Skill Level Intermediate
AngularJS 1: Building a Data-Driven Appwith Ray Villalobos2h 15m Intermediate
1. Controllers to Directives
2. Use controllerAs
Convert a controller’s code1m 57s
3. Directives to Components
4. Component Lifecycle Hooks
5. One-Way Data Binding
6. Testing Components
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