Ember.js MutableArray replace() Method

Last Updated : 23 Jul, 2025

Ember.js is an open-source JavaScript framework used for developing large client-side web applications 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 many websites, including Square, Discourse, Groupon, Linked In, Live Nation, Twitch, and Chipotle.

The replace() method is used to replace some of the elements in the array with the given objects.

Syntax:

replace(idx,amt,obj)

Parameters:

idx: Starting index to replace in the array
amt: The number of elements to be dropped from the array
obj: An array of items that should be added to the array, containing zero or more

Returns: It doesn't return anything.

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.hbs

{{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 "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}}