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Ember.js MutableArray reduce() Method

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  • Last Updated : 27 Sep, 2022
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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 Ember.js MutableArray reduce Method is used to combine the values of the array into a single value. This method is useful for collecting summaries from Array. 

Syntax: 

reduce( callback, initialValue ) ;

 

Parameters: 

  • callback: It is a function that will perform on each element of the array and return the result. 
  • initialValue: It is the initial value for the summary of the Array.

Return Value: This method returns a reduced value. 

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 details

app/route/party.js




import Route from '@ember/routing/route';
  
export default class PartyRoute extends Route {
    partyItems = [2, 3, 5, 6, 7, 8, 9, 2];
    ans;
    itemString;
    itemList;
    start;
    end;
    model() {
        return this.partyItems;
    }
    setupController(controller, model) {
        super.setupController(controller, model);
        controller.set('partyItems', this.partyItems);
        controller.set('ans', this.ans);
        controller.set('itemString', this.itemString);
        controller.set('itemList', this.itemList);
        controller.set('start', this.start);
        controller.set('end', this.end);
    }
}


app/controller/party.js




import Ember from 'ember';
import {
    toArray,
    unshiftObject,
    unshiftObjects,
    removeAt,
    reduce,
} from '@ember/array';
  
export default Ember.Controller.extend({
    actions: {
        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);
        },
        sumItems() {
            let ans = this.partyItems.reduce(function
                (accum, curr) {
                return accum + curr;
            });
            alert('Sum of Array is ' + ans);
        },
    },
});


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 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>
    <input type="button" id="sum-items" 
      value="Item sum" {{action "sumItems"}} />
</div>
{{outlet}}


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

Ember.js MutableArray reduce

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

ember generate route fruits

app/route/fruits.js




import Ember from "ember";
import { shiftObject, isAny, isEvery } 
    from "@ember/array";
  
export default Ember.Controller.extend({
    actions: {
        removeFruit() {
            this.fruits.shiftObject();
        },
        anyFruit() {
            let Fruit_presence = 
                this.fruits.reduce(function (accum, curr) {
                return accum || curr['isFruit'];
            }, true);
            //alert(`${'isFruit' in this.fruits[0]}`);
            alert(`${Fruit_presence ? "Yes" : "No"}`);
        },
        allFruit() {
            let Fruit_presence = 
                this.fruits.reduce(function (accum, curr) {
                return accum && curr['isFruit'];
            }, true);
            //alert(`${'isFruit' in this.fruits[0]}`);
            alert(`${Fruit_presence ? "Yes" : "No"}`);
        },
    },
});


app/controller/fruits.js




import Ember from "ember";
import { shiftObject, isAny, isEvery } from "@ember/array";
  
export default Ember.Controller.extend({
    actions: {
        removeFruit() {
            this.fruits.shiftObject();
        },
        anyFruit() {
            let Fruit_presence = this.fruits.reduce
                (function (accum, curr) {
                return accum || curr['isFruit'];
            }, true);
            //alert(`${'isFruit' in this.fruits[0]}`);
            alert(`${Fruit_presence ? "Yes" : "No"}`);
        },
        allFruit() {
            let Fruit_presence = this.fruits.reduce
                (function (accum, curr) {
                return accum && curr['isFruit'];
            }, true);
            //alert(`${'isFruit' in this.fruits[0]}`);
            alert(`${Fruit_presence ? "Yes" : "No"}`);
        },
    },
});


app/templates/fruits.hbs




{{page-title "Fruits"}}
<h3>Here is a list of eatables: </h3>
<ul>
    {{#each @model as |eatable|}}
        <li style="color: {{eatable.color}}">
      {{eatable.name}}</li>
      {{/each}}
</ul>
<br /><br />
<input
    type="button"
      id="remove-eatable"
      value="Remove Eatable"
      {{action "removeFruit"}}
/>
<br /><br />
<input
    type="button"
      id="fruit-any"
      value="List Contains Any Fruit?"
      {{action "anyFruit"}}
/>
<br /><br />
<input
    type="button"
      id="fruit-all"
      value="List Contains Only Fruit?"
      {{action "allFruit"}}
/>
{{outlet}}


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

Ember.js MutableArray reduce

Reference: https://api.emberjs.com/ember/4.4/classes/MutableArray/methods/reduce?anchor=reduce


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