Embeer.js MutableArray objectAt()用法及代码示例

Ember.js 是一个开源 JavaScript 框架，用于开发基于 Model-View-Controller (MVC) 架构的大型客户端 Web 应用程序。 Ember.js是使用最广泛的前端应用框架之一。它的目的是加速开发并提高生产力。目前，它被大量网站使用，包括 Square、Discourse、Groupon、Linked In、Live Nation、Twitch 和 Chipotle。

objectAt() 方法用于检索给定索引处的对象。

用法:

objectAt(index)

参数：

index:元素的索引。

返回值：所需的对象。

要运行以下示例，您需要有一个 ember 项目。要创建一个，您需要先安装ember-cli。在终端中写入以下代码：

npm install ember-cli

现在您可以通过输入以下代码来创建项目：

ember new <project-name> --lang en

要启动服务器，请键入：

ember serve

示例 1：键入以下代码以生成本示例的路由：

ember generate route party

应用程序/路线/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); 
    } 
}

应用程序/控制器/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', ''); 
        }, 
    }, 
});

应用程序/模板/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}}

输出：访问 localhost:4200/party 查看输出

示例 2：键入以下代码以生成本示例的路由：

ember generate route details

应用程序/路线/details.js


import Route from '@ember/routing/route'; 
  
export default class DetailsRoute extends Route { 
  details = [ 
    { 
      name: 'Anubhav', 
      mobile: '1298119967', 
      city: 'Patna', 
      country: 'India', 
      gender: 'M', 
      zipCode: '800020', 
    }, 
    { 
      name: 'Sakshi', 
      mobile: '1234567890', 
      city: 'Mumbai', 
      country: 'India', 
      gender: 'F', 
      zipCode: '400001', 
    }, 
    { 
      name: 'Satyam', 
      mobile: '2222222222', 
      city: 'Delhi', 
      country: 'India', 
      gender: 'M', 
      zipCode: '110012', 
    }, 
    { 
      name: 'Shivam', 
      mobile: '1122113322', 
      city: 'Bangalore', 
      country: 'India', 
      gender: 'M', 
      zipCode: '530068', 
    }, 
    { 
      name: 'Ayushi', 
      mobile: '2244668800', 
      city: 'Jaipur', 
      country: 'India', 
      gender: 'F', 
      zipCode: '302001', 
    }, 
  ]; 
  someMoreDetails = [ 
    { 
      name: 'Yeshwant', 
      mobile: '1133557799', 
      city: 'Chennai', 
      country: 'India', 
      gender: 'M', 
      zipCode: '600001', 
    }, 
    { 
      name: 'Siddhant', 
      mobile: '9911000000', 
      city: 'Mangalore', 
      country: 'India', 
      gender: 'M', 
      zipCode: '574142', 
    }, 
    { 
      name: 'Khushi', 
      mobile: '8888888888', 
      city: 'Pune', 
      country: 'India', 
      gender: 'F', 
      zipCode: '111045', 
    }, 
  ]; 
  start; 
  end; 
  idx; 
  model() { 
    return this.details; 
  } 
  setupController(controller, model) { 
    super.setupController(controller, model); 
    controller.set('details', this.details); 
    controller.set('someMoreDetails',  
        this.someMoreDetails); 
    controller.set('start', this.start); 
    controller.set('end', this.end); 
    controller.set('idx', this.idx); 
  } 
}

应用程序/控制器/details.js


import Ember from 'ember'; 
import { removeAt, unshiftObjects, objectAt, 
         uniqBy, find } from '@ember/array'; 
  
export default Ember.Controller.extend({ 
  actions: { 
    removeDetails(start,end) { 
      this.details.removeAt(start,end); 
    }, 
    addMoreDetails() { 
      this.details.unshiftObjects(this.someMoreDetails); 
    }, 
    getDetail(index) { 
      let foo = this.details.objectAt(index); 
      alert(foo.name); 
    }, 
    getFirstMaleAndFemalePerson() { 
      let foo = this.details.uniqBy('gender').toArray(); 
      let str = ""; 
      for (let i = 0; i < foo.length; i++) 
        str += foo[i].name + "\n"; 
      alert(str); 
    }, 
    getFirstMale() { 
      let foo = this.details.find( 
          (detail) => detail.gender === 'M'); 
      alert(foo.name); 
    }, 
  }, 
});

应用程序/模板/details.js


{{page-title "Details"}} 
<h3>List of People: </h3> 
<br /><br /> 
<table> 
    <tr> 
        <th>Name</th> 
        <th>Gender</th> 
        <th>Mobile</th> 
        <th>City</th> 
        <th>Country</th> 
        <th>Zip Code</th> 
    </tr> 
    {{#each @model as |detail|}} 
    <tr> 
        <td>{{detail.name}}</td> 
        <td>{{detail.gender}}</td> 
        <td>{{detail.mobile}}</td> 
        <td>{{detail.city}}</td> 
        <td>{{detail.country}}</td> 
        <td>{{detail.zipCode}}</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> 
<br /><br /> 
<input type="button" id="add-details" 
       value="Add More Details" 
       {{action 'addMoreDetails' }} /> 
<br /><br /> 
<input type="button" id="all-male" 
       value="Get First Male" 
       {{action 'getFirstMale' }} /> 
<br /><br /> 
<input type="button" id="get" value="Get" 
       {{action 'getFirstMaleAndFemalePerson' }} /> 
{{outlet}}

输出：访问 localhost:4200/details 查看输出

参考： https://api.emberjs.com/ember/4.4/classes/MutableArray/methods

相关用法

注：本文由纯净天空筛选整理自aayushmohansinha大神的英文原创作品 Ember.js MutableArray objectAt() Method。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。