Embeer.js MutableArray lastIndexOf()用法及代碼示例

Ember.js 是一個開源 JavaScript 框架，用於開發基於 Model-View-Controller (MVC) 架構的大型客戶端 Web 應用程序。 Ember.js是使用最廣泛的前端應用框架之一。它的目的是加速開發並提高生產力。目前，它被大量網站使用，包括 Square、Discourse、Groupon、Linked In、Live Nation、Twitch 和 Chipotle。

lastIndexOf() 方法用於查找數組中對象的最後一個索引。

用法:

lastIndexOf(object,startAt)

參數：

object: 要尋找的對象。
startAt:從哪裏搜索的索引

返回值：給定對象出現的最後一個索引。如果該對象不存在，則返回 -1。

第 1 步：要運行以下示例，您需要有一個 ember 項目。要創建一個，您需要先安裝ember-cli。在終端中寫入以下代碼：

npm install ember-cli

現在您可以通過輸入以下代碼來創建項目：

ember new <project-name> --lang en

步驟 2：要啟動服務器，請鍵入：

ember serve

示例 1：鍵入以下代碼以生成本示例的路由：

ember generate route list

應用程序/路線/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); 
    } 
}

應用程序/控製器/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}`); 
        }, 
    }, 
});

應用程序/模板/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}}

輸出：訪問 localhost:4200/list 查看輸出

示例 2：鍵入以下代碼以生成本示例的路由：

ember generate route party

應用程序/路線/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); 
    } 
}

應用程序/控製器/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}`); 
        }, 
    }, 
});

應用程序/模板/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}}

輸出：訪問 localhost:4200/party 查看輸出

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

相關用法

注：本文由純淨天空篩選整理自aayushmohansinha大神的英文原創作品 Ember.js MutableArray lastIndexOf() Method。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。