Ember.js MutableArray lastIndexOf() 方法

Ember.js 是一个开源的JavaScript框架，用于开发基于模型-视图-控制器（MVC）架构的大型客户端Web应用程序。 Ember.js是最广泛使用的前端应用程序框架之一。它旨在加快开发速度和提高生产力。目前，许多网站使用它，包括Square，Discourse，Groupon，Linked In，Live Nation，Twitch和Chipotle。

lastIndexOf()方法 用于找到数组中对象的最后一个索引。

语法：

lastIndexOf(object,startAt)

参数：

object： 要查找的对象。
startAt： 从哪里开始搜索的索引

返回值： 给定对象出现的最后一个索引。如果对象不存在，则返回-1。

步骤1： 要运行以下示例，您需要拥有一个ember项目。要创建一个项目，您需要首先安装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

步骤2： 启动服务器，请键入：

ember serve

示例1

输入以下代码以生成此示例的路由：

ember generate route list

app/routes/list.js

import Route from '@ember/routing/route'; 
  
export default class ListRoute extends Route { 
    list = ['a', 'a', 'v', 'c', 'c', 'a',  
    'd', 'q', 'b', 'z', 'a']; 
    item; 
    idx; 
    model() { 
        return this.list; 
    } 
    setupController(controller, model) { 
        super.setupController(controller, model); 
        controller.set('list', this.list); 
        controller.set('item', this.item); 
        controller.set('idx', this.idx); 
    } 
}

app/controllers/list.js

import Ember from 'ember'; 
import { clear, insertAt, indexOf, lastIndexOf,  
    includes } from '@ember/array'; 
  
export default Ember.Controller.extend({ 
    actions: { 
        insertItem(item, idx) { 
            this.list.insertAt(idx, item); 
        }, 
        getLastIndex(item) { 
            let res = this.list.lastIndexOf(item); 
            alert(res); 
        }, 
        getFirstIndex(item) { 
            let res = this.list.indexOf(item); 
            alert(res); 
        }, 
        clearList() { 
            this.list.clear(); 
        }, 
        contains(item) { 
            let res = this.list.includes(item); 
            alert(`The list  ${res ? '' : 'does not'} contains$ {item}`); 
        }, 
    }, 
});

app/template/list.hbs

{{page-title "List"}} 
<h3>Here is a list of Items: </h3> 
<ul> 
    {{#each @model as |i|}} 
    <li>{{i}}</li> 
    {{/each}} 
</ul> 
<br /><br /> 
<div> 
    <label>Enter Item: </label> 
      {{input value=this.item}} 
</div> 
<div> 
    <label>Enter Index: </label> 
    {{input value=this.idx}} 
</div> 
<div> 
    <input
        type="button"
        id="insert-item"
        value="Insert Item"
        {{action "insertItem" this.item this.idx}} 
      /> 
</div> 
<br /><br /> 
<div> 
    <label>Enter Item: </label> 
    {{input value=this.item}} 
</div> 
<div> 
    <input
        type="button"
        id="first-index-item"
        value="Get First Index"
        {{action "getFirstIndex" this.item}} 
  /> 
</div> 
<div> 
    <input
        type="button"
        id="last-index-item"
        value="Get Last Index"
        {{action "getLastIndex" this.item}} 
    /> 
</div> 
<div> 
    <input
        type="button"
        id="contains-item"
        value="Contains?"
        {{action "contains" this.item}} 
      /> 
</div> 
<br /><br /> 
<input type="button" id="clear-items" 
    value="Clear" {{action "clearList"}} /> 
{{outlet}}

输出： 访问 localhost:4200/list 查看输出

Ember.js MutableArray lastIndexOf() 方法

示例2

输入以下代码生成此示例的路由:

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', 
        'Cold Drink', 
        'Balloons', 
        'Scissors', 
        'Wine', 
        'Cold Drink', 
        'Table Confetti', 
        'Party Hats', 
        'Wine', 
        'Napkins', 
        'Party Plates', 
        'Speakers', 
        'Wine', 
        'Music System', 
        'Cold Drink', 
        'Cups', 
    ]; 
    item; 
    idx; 
    model() { 
        return this.partyItems; 
    } 
    setupController(controller, model) { 
        super.setupController(controller, model); 
        controller.set('partyItems', this.partyItems); 
        controller.set('item', this.item); 
        controller.set('idx', this.idx); 
    } 
}

app/controllers/party.js

import Ember from 'ember'; 
import { insertAt, indexOf, lastIndexOf, 
    includes } from '@ember/array'; 
  
export default Ember.Controller.extend({ 
    actions: { 
        insertItem(item, idx) { 
            this.partyItems.insertAt(idx, item); 
        }, 
        getLastIndex(item) { 
            let res = this.partyItems.lastIndexOf(item); 
            alert(res); 
        }, 
        getFirstIndex(item) { 
            let res = this.partyItems.indexOf(item); 
            alert(res); 
        }, 
        clearpartyItems() { 
            this.partyItems.clear(); 
        }, 
        contains(item) { 
            let res = this.partyItems.includes(item); 
            alert(`The partyItems  ${res ? '' : 'does not'} contains$ {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> 
    <label>Enter Index: </label> 
    {{input value=this.idx}} 
</div> 
<div> 
    <input
        type="button"
        id="insert-item"
        value="Insert Item"
        {{action "insertItem" this.item this.idx}} 
  /> 
</div> 
<br /><br /> 
<div> 
    <label>Enter Item: </label> 
    {{input value=this.item}} 
</div> 
<div> 
    <input
        type="button"
        id="first-index-item"
        value="Get First Index"
        {{action "getFirstIndex" this.item}} 
  /> 
</div> 
<div> 
    <input
        type="button"
        id="last-index-item"
        value="Get Last Index"
        {{action "getLastIndex" this.item}} 
    /> 
</div> 
<div> 
    <input
        type="button"
        id="contains-item"
        value="Contains?"
        {{action "contains" this.item}} 
    /> 
</div> 
<br /><br /> 
{{outlet}}

输出: 访问 localhost:4200/party 来查看输出

Ember.js MutableArray lastIndexOf() 方法