Ember.js EmberArray objectAt() 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 objectAt() method is used to retrieve the object at a given index. If we used a negative number or number which is greater than the size of the Array then this method returns undefined.

Syntax:

objectAt(index)

Parameters:

• index: It is the index of elements that we want.

Return Value: Item at the index.

Steps to Install and Run Ember.js:

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

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 objectAt1

app/routes/objectAt1.js

import Route from '@ember/routing/route';

class student {
    name = null;
    gender = null;
    class = null;
    grade = null;
    constructor(name, gender, class, grade) {
        this.name = name;
        this.gender = gender;
        this.class = class;
        this.grade = grade
    }

    show_grade() {
        return `I am ${this.name} of
        Class ${this.class} Get ${this.grade}`;

    }
}

export default class StudentsRoute
    extends Route {
    students =
        [new student('Aakash', 'M', 10, 'A',),
        new student('Soniya', 'F', 8, 'C'),
        new student('Esnoor', 'M', 9, 'C'),
        new student('Isha', 'F', 11, 'B',),
        new student('Doman', 'M', 12, 'B'),
        new student('Lolu', 'M', 10, 'A'),
        new student('Satyam', 'M', 10, 'A'),
        ];
    temp2;
    temp;
    model() {
        return this.students;
    }
    setupController(controller, model) {
        super.setupController(controller, model);
        controller.set('students', this.students);
        controller.set('temp', this.temp);
        controller.set('temp1', this.temp1);
        controller.set('temp2', this.temp2);
    }
}

app/controllers/objectAt1.js

import Ember from 'ember';
import { mapBy } from '@ember/array';

export default Ember.Controller.extend({
    actions: {
        removeDetails(start,end) {
            this.students.removeAt(start,end);
          },
          getDetail(index) {
            let foo = this.students.objectAt(index);
            alert(`${foo.name} of class ${foo.class}`);
          },

    },
});

app/templates/objectAt1.hbs

{{page-title "Student"}}
<h3>List of Students: </h3>
<br /><br />
<table>
    <tr>
        <th>Name</th>
        <th>Gender </th>
        <th>Class </th>
        <th>Grade </th>
    </tr>
    {{#each @model as |detail|}}
        <tr>
            <td>{{detail.name}}</td>
            <td> {{detail.gender}}</td>
            <td>{{detail.class}}</td>
            <td>{{detail.grade}}</td>
        </tr>
    {{/each}}
</table>

<br />
<br /><div>
    <label>Enter Start Index: </label>
    {{input value=this.start}}
</div>
<div>
    <label>Enter End Index: </label>
    {{input value=this.end}}
</div>
<div>
    <input
        type="button"
        id="remove-details"
        value="Remove Details"
        {{action "removeDetails"
         this.start this.end}}
    />
</div>
<br /><br />
<div>
    <label>Enter Index: </label>
    {{input value=this.idx}}
</div>
<div>
    <input
        type="button"
        id="get-detail"
        value="Get detail"
        {{action "getDetail" this.idx}}
    />
</div>
{{outlet}}

Output: Visit localhost:4200/objectAt1 to view the output

Ember.js EmberArray objectAt method

Example 2: Type the following code to generate the route for this example:

ember generate route objectAt2

app/routes/objectAt2.js

import Route from '@ember/routing/route';
import { } from '@ember/array';

export default class FruitsRoute
    extends Route {
    item1 = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
    item2 = ['l', 'm', 'h', 'i', 'j', 'k'];
    model() {
        return this.item1;
    }
    setupController(controller, model) {
        super.setupController(controller, model);
        controller.set('item1', this.item1);
        controller.set('item2', this.item2)
    }
}

app/controllers/objectAt2.js

import Ember from 'ember';
import { removeAt, unshiftObjects, objectAt,
        uniqBy, find } from '@ember/array';

export default Ember.Controller.extend({
    actions: {
        Show_item(start, end) {
            let foo = this.item1.objectAt(start);
            alert(foo);
        },
        Push_item() {
            this.item1.pushObjects(this.item2)
        },
    },
});

app/templates/objectAt2.hbs

{{page-title "Fruits"}}
<table style=" border-spacing : 30px">
<h3>Here is a list 1: </h3>
<ul>
    {{#each @model as |item|}}
    <li>{{item}}</li>
    {{/each}}
</ul>
</table>
<div>
    <label>Enter Start Index: </label>
    {{input value=this.start}}
</div>
<div>
    <input type="button"
        id="show-details"
        value="Show Items"
        {{action 'Show_item' this.start}} />
</div>
<br /><br />
<input type="button" id="push-item"
    value="Push More Items"
    {{action 'Push_item' }} />


{{outlet}}

Output: Visit localhost:4200/objectAt2 to view the output

Ember.js EmberArray objectAt method

Reference: https://api.emberjs.com/ember/2.14/classes/Ember.Array/methods/objectAt?anchor=objectAt