Ember.js ObjectProxy decrementProperty() Method

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

export default class WebsitesRoute extends Route {

    food = [
        EmberObject.create({
            food: 'apple',
            isFruit: true,
            quant: 3,
        }),
        EmberObject.create({
            food: 'Potato',
            isFruit: false,
            quant: 4,
        }),
        EmberObject.create({
            food: 'Banana',
            isFruit: true,
            quant: 2,
        }),
        EmberObject.create({
            food: 'Burgur',
            isFruit: false,
            quant: 2,
        }),
        EmberObject.create({
            food: 'Orange',
            isFruit: true,
            quant: 7,
        }),
    ];

    temp;
    model() {
        return this.food;
    }
    setupController(controller, model) {
        super.setupController(controller, model);
        controller.set('food', this.food);
        controller.set('temp', this.temp);
        controller.set('food2', this.food2);
    }
}

import Ember from 'ember';

export default Ember.Controller.extend({
    value: 0,
    actions: {
        remove_item(item) {
            this.food.set('[]', this.food.without
                (this.food.findBy('food', item)));
        },

        list() {
            let ans = '';
            this.food.forEach((item) => ans += 
                item.get('food') + '\n');
            alert(ans)
        },
        increase() {
            this.food.forEach((item) => 
                item.incrementProperty('quant'));
        },
        decrease() {
            this.food.forEach((item) => 
                item.decrementProperty('quant'));
        },
    },
});

{{page-title "decrementProperty"}}
<h3>List of Item in Buckets</h3>
<table>
    <tr>
        <th> Food_Name </th>
        <th>Bucket </th>
        <th>Fruit </th>
    </tr>
      {{#each @model as |website|}}
        <tr>
            <td>{{website.food}}</td>
              <td>{{website.quant}}</td>
              <td>{{website.isFruit}}</td>
        </tr>
      {    {/each}}
</table>
<br />
<div>
    <label>Enter value: </label>
      {{input value=this.item}}
</div>
<input
    type="button"
      id="R-item"
      value="Remove this item"
      {{action "remove_item" this.item}}
/>
<br /><br />
<input 
    type="button" 
    id="list-items" 
    value="List All Items" 
    {{action "list"}} />
<br /><br />
<input
    type="button"
      id="increase-property"
      value="Increase Quantity"
      {{action "increase"}}
/>
<br /><br />
<input
    type="button"
      id="decrease-property"
      value="dcrease Quantity"
      {{action "decrease"}}
/>
{{outlet}}

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

export default class FruitsRoute extends Route {
     students = [
        EmberObject.create({ name : 'Rahul', 
            Class : 11, marks : 75}),
        EmberObject.create({name : 'Sam',    
            Class : 12,marks : 59}),
        EmberObject.create({name : 'David',  
            Class : 11,marks : 67}),
        EmberObject.create({name : 'Druv',   
            Class : 12,marks : 44}),
        EmberObject.create({name : 'Mahan',  
            Class : 12,marks : 87}),
        EmberObject.create({name : 'Ram',    
            Class : 11,marks : 71}),
        EmberObject.create({name : 'Dadu',   
            Class : 12,marks : 58})
       ];
    model() {
        return this.students;
    }
    setupController(controller,model) {
        super.setupController(controller, model);
        controller.set('students', this.students);
    }
}

import Ember from "ember";
import { isAny, isEvery } from "@ember/array";

export default Ember.Controller.extend({
    actions: {
        increase(data) {
            this.students.forEach((item) => 
                item.incrementProperty('marks', JSON.parse(data)));
        },
        decrease(data) {
            this.students.forEach((item) => 
                item.decrementProperty('marks', JSON.parse(data)));
        },
        remove(item) {
            this.students.set('[]', 
                this.students.without(this.students.findBy
                ('name', item)));
        },
        show_first() {
            let ans = this.students.get('firstObject');
            alert(ans.name)
        },
        show_last() {
            let ans = this.students.get('lastObject');
            alert(ans.name)
        },
    },
});

{{page-title "decrementProperty"}}
<h3>Students List: </h3>
<table>
    <tr>
        <th>Name</th>
        <th>Class</th>
        <th>Marks</th>
      </tr>
      {{#each @model as |detail|}}
    <tr>
        <td>{{detail.name}}</td>
          <td>{{detail.Class}}</td>
          <td>{{detail.marks}}</td>
    </tr>
      {{/each}}
</table>
<br />
<div>
    <label>Enter value: </label>
      {{input value=this.item}}
</div>
<input
    type="button"
      id="increase-marks"
      value="Increase All marks by Value"
      {{action "increase" this.item}}
/>
<br /><br />
<div>
    label>Enter value: </label>
      {{input value=this.item2}}
</div>
<input
    type="button"
      id="decrease-marks"
      value="decrease All marks by Value"
      {{action "decrease" this.item2}}
/>
<br /><br />
<div>
    <label>Enter Name: </label>
      {{input value=this.item3}}
</div>
<input
    type="button"
      id="remove-student"
      value="Remove Student"
      {{action "remove" this.item3}}
/>
<br /><br />
<input
    type="button"
      id="first-student"
      value="Show First Student in list"
      {{action "show_first"}}
/>
<br /><br />
<input
    type="button"
      id="last-student"
      value="Show Last Student in list"
      {{action "show_last"}}
/>
{{outlet}}