Ember.js Route addObserver() Method
Ember.js is an open-source JavaScript framework used for developing large client-side web applications which is based on Model-View-Controller (MVC) architecture. Ember.js is one of the most widely used front-end application frameworks. It is made to speed up development and increase productivity. Currently, it is utilized by a large number of websites, including Square, Discourse, Groupon, Linked In, Live Nation, Twitch, and Chipotle.
The addObserver() method is used to register the observer to the property.
Syntax:
addObserver( key, target, method, sync );
Parameters:
- key: It is the key that will be observed.
- target: It is the object for which the observer will invoke.
- method: It is the method name that will invoke when the observer gets something.
- sync: It defines whether to sync the observer or not.
Return: Observable.
Steps to Install and Run Ember.js:
Step 1: To run the following examples you will need to have an ember project with you. To create one, you will need to install ember-cli first. Write the below code in the terminal:
npm install ember-cli
Step 2: Now you can create the project by typing in the following piece of code:
ember new <project-name> --lang en
To start the server, type:
ember serve
Example 1: Type the following code to generate the route for this example:
ember generate route addObserver1
app/components/arr.js
Javascript
import Component from '@glimmer/component' ; import Ember from 'ember' ; import { tracked } from '@glimmer/tracking' ; import { action, addObjects, set, get } from '@ember/object' ; export default Ember.Component.extend({ value: 'Oxygen' , init() { this ._super(...arguments); this .addObserver( 'value' , this , 'change' ); alert( 'Route Init() is initiated' ); }, change() { console.log( 'Value changed ' ) }, p1: [ 'Oxygen' , 'Source Code' , 'Infinite' , 'Tenet' , 'SpiderHead' , 'The Thing' , 'A Quiet Place' , 'The Invisible Man' , 'Looper' , 'Ad Astra' , ], @action remove(data) { this .p1.set( '[]' , this .p1.without(data)); }, @action print(){ let ans = this .p1.get( '[]' ); alert(ans.join( '\n' )) } }) |
app/components/arr.hbs
HTML
< ul > < h3 >{{yield}} </ h3 > {{#each this.p1 as |party|}} < li >{{party}}</ li > {{/each}} </ ul > < br /> {{input value=this.value}} < br /> < input type = "button" id = "check-atIndex" value = "Remove" {{action "remove" this.value}} /> < br />< br /> < input type = "button" id = "print-item" value = "Print All Items" {{action "print"}} /> |
- app/templates/addObserver.hbs
HTML
< Arr > < h3 >List is : </ h3 ></ Arr > |
Output:
Example 2: Type the following code to generate the route for this example:
ember generate route addObserver2
app/components/arr2.js
Javascript
import Component from '@glimmer/component' ; import { tracked } from '@glimmer/tracking' ; import { action } from '@ember/object' ; import { mapBy } from '@ember/object' ; import Ember from 'ember' ; let Student = Ember.Object.extend({ // these will be supplied by `create` firstName: null , lastName: null , fullName: Ember.computed( 'firstName' , 'lastName' , function () { return `${ this .firstName} ${ this .lastName}`; }), Changed: Ember.observer( 'fullName' , function () { console.log(`fullName changed to: ${ this .fullName}`); }), }); export default Ember.Component.extend({ students: [ Student.create({ firstName: 'Kasual' , lastName: 'Singh' , Id: 'stu2' , }), Student.create({ firstName: 'Yehuda' , lastName: 'Katz' , Id: 'stu0' , }), Student.create({ firstName: 'Yella' , lastName: 'melo' , Id: 'stu1' , }), Student.create({ firstName: 'Pokhu' , lastName: 'Verma' , Id: 'stu3' , })], @tracked value: 'Pokhu' , @tracked value2: 'Pokhraj' , @action print(data1, data2) { let ans = this .students.find((item) => item.get( 'firstName' ) == data1) ans.set( 'lastName' , data2) } }) |
app/components/arr2.hbs
HTML
{{yield}} < table > < tr > < th >Name</ th > < th >Id</ th > </ tr > {{#each this.students as |detail|}} < tr > < td >{{detail.fullName}}</ td > < td >{{get detail "Id"}}</ td > </ tr > {{/each}} </ table > < br /> {{input value=this.value}} {{input value=this.value2}} < br /> < input type = "button" id = "set-code" value = "Update Student details" {{action "print" this.value this.value2}} /> |
app/templates/addObserver2.hbs
HTML
< Arr2 >< h3 >Students Details :</ h3 ></ Arr2 > |
Output:
Reference: https://api.emberjs.com/ember/4.6/classes/Route/methods/addObserver?anchor=addObserver
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