Ember.js MutableArray unshiftObject() Method

Last Updated : 23 Jul, 2025

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 unshiftObject() method is used to add a single object to the start of the array.

Syntax:

unshiftObject(obj)

Parameters:

obj: The object to be added.

Return Value: The new array.

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 party

app/routes/party.js

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

export default class PartyRoute extends Route {
    partyItems = [
        'Digital Camera',
        'Jugs, cups & straws',
        'Balloons',
        'Scissors',
        'Cold Drink',
        'Table Confetti',
        'Party Hats',
        'Wine',
        'Napkins',
        'Party Plates',
        'Speakers',
        'Music System',
        'Cups',
    ];
    item;
    itemString;
    itemList;
    start;
    end;
    idx;
    model() {
        return this.partyItems;
    }
    setupController(controller, model) {
        this._super(controller, model);
        controller.set('partyItems', this.partyItems);
        controller.set('item', this.item);
        controller.set('itemString', this.itemString);
        controller.set('itemList', this.itemList);
        controller.set('start', this.start);
        controller.set('end', this.end);
        controller.set('idx', this.idx);
    }
}

app/controllers/party.js

import Ember from 'ember';
import {
    without, toArray, unshiftObject, unshiftObjects,
    removeAt, objectAt, find, replace, uniq
}
    from '@ember/array';

export default Ember.Controller.extend({
    actions: {
        withoutItem(item) {
            console.log(item)
            let tempItems;
            tempItems = this.partyItems.without(item);
            let str = '';
            for (let i = 0; i < tempItems.length; i++)
                str += tempItems[i] + '\n';
            alert(str);
            this.set('item', '');
        },
        addItems(itemString) {
            this.itemList = itemString.split(',').toArray();
            if (this.itemList.length == 1)
                this.partyItems.unshiftObject(this.itemList[0]);
            else
                this.partyItems.unshiftObjects(this.itemList);
            this.set('itemString', '');
        },
        removeItems(start, end) {
            this.partyItems.removeAt(start, end);
        },
        getObject(idx) {
            alert(`The item at index ${idx} is 
            ${this.partyItems.objectAt(idx)}`);
        },
        findMultipleWordItems() {
            let reqItem = this.partyItems.find((item) => 
            item.split(' ').toArray().length > 1);
            alert(reqItem);
        },
        replaceItem(itemString) {
            this.itemList = itemString.split(',').toArray();
            if (this.itemList.length > this.partyItems.length)
                alert('Error');
            this.partyItems.replace(0, this.itemList.length,
                                    this.itemList);
        },
        getUniqueItems() {
            let tempItems = this.partyItems.uniq();
            let str = '';
            for (let i = 0; i < tempItems.length; i++)
                str += tempItems[i] + '\n';
            alert(str);
            this.set('item', '');
        },
    },
});

app/template/party.js

{{page-title "Party"}}
<h3>Here is a list of items: </h3>
<ul>
    {{#each @model as |party|}}
    <li>{{party}}</li>
    {{/each}}
</ul>
<br /><br />
<div>
    <label>Enter Item: </label>
    {{input value=this.item}}
</div>
<div>
    <input type="button" id="remove-item" 
           value="Remove Item" 
           {{action 'withoutItem' this.item}} />
</div>
<br /><br />
<div>
    <label>Enter Items: </label>
    {{input value=this.itemString}}
</div>
<div>
    <input type="button" id="add-item" 
           value="Add Items" 
           {{action 'addItems' this.itemString}} />
</div>
<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-items" 
           value="Remove Items"
           {{action 'removeItems' this.start this.end}} />
</div>
<br /><br />
<div>
    <label>Enter Index: </label>
    {{input value=this.idx}}
</div>
<div>
    <input type="button" id="get-item" 
           value="Get Item" 
           {{action 'getObject' this.idx}} />
</div>
<br /><br />
<div>
    <label>Enter Items: </label>
    {{input value=this.itemString}}
</div>
<div>
    <input type="button" id="replace-item" 
           value="Replace Items" 
           {{action 'replaceItem' this.itemString}} />
</div>
<br /><br />
<input type="button" id="get-multiword" 
       value="Get Multiword Items!" 
       {{action 'findMultipleWordItems' }} />
<br /><br />
<input type="button" id="get-unique" 
       value="Get Unique Items!" 
       {{action 'getUniqueItems' }} />
{{outlet}}

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

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

ember generate route notepad

app/routes/notepad.js

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

export default class NotepadRoute extends Route {
    items = [];
    item;
    model() {
        return this.items;
    }
    setupController(controller, model) {
        super.setupController(controller, model);
        controller.set('items', this.items);
    }
}

app/controllers/notepad.js

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

export default Ember.Controller.extend({
    actions: {
        withoutItem(item) {
            let tempItems;
            tempItems = this.items.without(item);
            let str = '';
            for (let i = 0; i < tempItems.length; i++)
                str += tempItems[i] + '\n';
            alert(str);
            this.set('item', '');
        },
        replaceItem(item) {
            let itemList = item.split(',').toArray();
            if (itemList.length > this.items.length)
                alert('Error');
            this.items.replace(0, itemList.length, itemList);
        },
        addItem(item) {
            this.items.unshiftObject(item);
        },
        getUniqueItems() {
            let tempItems = this.items.uniq();
            let str = '';
            for (let i = 0; i < tempItems.length; i++)
                str += tempItems[i] + '\n';
            alert(str);
            this.set('item', '');
        },
    },
});

app/template/notepad.hbs

{{page-title "Notepad"}}
<h2>Notepad</h2>
<div>
    <label>Enter Item: </label>
    {{input value=this.item}}
</div>
<div>
    <input type="button" id="add-item" 
           value="Add Item" 
           {{action 'addItem' this.item}} />
</div>
<br /><br />
<ul>
    {{#each @model as |item|}}
    <li>{{item}}</li>
    {{/each}}
</ul>

<br /><br />
<div>
    <label>Enter Item: </label>
    {{input value=this.item}}
</div>
<div>
    <input type="button" id="without-item" 
           value="Without Item" 
           {{action 'withoutItem' this.item}} />
</div>
<br /><br />
<div>
    <label>Enter Item: </label>
    {{input value=this.item}}
</div>
<div>
    <input type="button" id="replace-item" 
           value="Replace Item"
           {{action 'replaceItem' this.item}} />
</div>
<br /><br />
<input type="button" id="get-unique" 
       value="Get Unique Items!" 
       {{action 'getUniqueItems' }} />
{{outlet}}