Embeer.js ArrayProxy mapBy()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。

mapBy() 方法用于获取枚举中命名属性的所有值。

用法:

mapBy( key );

参数：

key:它是我们想要其值的属性的名称。

返回值：返回映射数组。

第 1 步：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

第 2 步：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 mapBy1

应用程序/路线/mapBy1.js


import Route from "@ember/routing/route"; 
  
export default class StudentsRoute extends Route { 
    students = [ 
        { 
            name: "Aaush Somankar", 
            gender: "M", 
            class: 12, 
            grade: "A", 
        }, 
        { 
            name: "Aman Prakash", 
            gender: "M", 
            class: 10, 
            grade: "A", 
        }, 
        { 
            name: "Siya guru", 
            gender: "F", 
            class: 11, 
            grade: "B", 
        }, 
        { 
            name: "Ramesh verma", 
            gender: "M", 
            class: 10, 
            grade: "A", 
        }, 
        { 
            name: "Esnoor", 
            gender: "M", 
            class: 9, 
            grade: "F", 
        }, 
        { 
            name: "Balit", 
            gender: "M", 
            class: 10, 
            grade: "A", 
        }, 
        { 
            name: "Dora", 
            gender: "F", 
            class: 12, 
            grade: "F", 
        }, 
        { 
            name: "Lalu", 
            gender: "F", 
            class: 8, 
            grade: "A", 
        }, 
        { 
            name: "Pokhraj", 
            gender: "M", 
            class: 11, 
            grade: "F", 
        }, 
        { 
            name: "Citu", 
            gender: "M", 
            class: 8, 
            grade: "C", 
        }, 
        { 
            name: "Rahul", 
            gender: "M", 
            class: 9, 
            grade: "A", 
  
        }, 
        { 
            name: "Ram", 
            gender: "M", 
            class: 12, 
            grade: "A", 
        }, 
        { 
            name: "Priti", 
            gender: "F", 
            class: 9, 
            grade: "F", 
        }, 
        { 
            name: "Flip", 
            gender: "M", 
            class: 9, 
            grade: "B", 
        }, 
        { 
            name: "Sita", 
            gender: "F", 
            class: 8, 
            grade: "A", 
        }, 
        { 
            name: "Aashray", 
            gender: "M", 
            class: 12, 
            grade: "C", 
        }, 
        { 
            name: "Suneel", 
            gender: "M", 
            class: 8, 
            grade: "C", 
        }, 
    ]; 
    convert(string) { 
        this.item = string.split(",").map((item) 
            => item.trim()); 
        return this.item; 
    } 
  
    model() { 
        return this.students; 
    } 
    setupController(controller, model) { 
        super.setupController(controller, model); 
        controller.set("students", this.students); 
        controller.set("convert", this.convert); 
        controller.set("item", this.item); 
    } 
}

应用程序/控制器/mapBy1.js


import Ember from "ember"; 
  
export default Ember.Controller.extend({ 
    actions: { 
        getAllNames() { 
            let res = this.students.mapBy('name'); 
            alert(res.join('\n')); 
        }, 
        allPass() { 
            let temp = ''; 
            let tempItems = this.students.map((item) =>  
                item.grade == 'F' ? temp += 
                item.name + '\n' : temp); 
            alert(temp); 
  
        }, 
        remove() { 
            this.students.popObject(); 
        }, 
        check_item(idx) { 
            let temp = this.students.objectAt(JSON.parse(idx)); 
            alert(temp.name) 
        }, 
        check_items(idx) { 
            idx = this.convert(idx); 
            let temp = this.students.objectsAt(idx); 
            let ans = temp.mapBy('name') 
            alert(ans.join('\n')) 
        }, 
  
    }, 
});

应用程序/模板/mapBy1.hbs


{{page-title "mapBy"}} 
<h3>List of Students: </h3> 
<table> 
    <tr> 
        <th>Name</th> 
        <th>Class</th> 
        <th>Gender</th> 
        <th>Grade</th> 
    </tr> 
    {{#each @model as |student|}} 
    <tr> 
        <td>{{student.name}}</td> 
        <td>{{student.class}}</td> 
        <td>{{student.gender}}</td> 
        <td>{{student.grade}}</td> 
    </tr> 
    {{/each}} 
</table> 
<br /><br /> 
<input 
    type="button"
    id="get-all"
    value="Get All Names"
    {{action "getAllNames"}} 
/> 
<br /><br /> 
<input 
    type="button"
    id="all-pass"
    value="Did Everyone Pass?"
    {{action "allPass"}} 
/> 
  
<br /><br /> 
<div> 
    <label>Enter index: </label> 
    {{input value=this.temp}} 
</div> 
<input 
    type="button"
    id="increase-pocket-money"
    value="Get Person at Index"
    {{action "check_item" this.temp}} 
/> 
<br /><br /> 
<div> 
    <label>Enter indexs: </label> 
    {{input value=this.temp2}} 
</div> 
<input 
    type="button"
    id="check-atIndex"
    value="Check at indexes"
    {{action "check_items" this.temp2}} 
/> 
<br /><br /> 
<input 
    type="button"
    id="remove-last"
    value="Remove Last Student"
    {{action "remove"}} 
/> 
{{outlet}}

输出：访问 localhost:4200/mapBy1 查看输出

Ember.js ArrayProxy mapBy 方法

示例 2：键入以下代码以生成本示例的路由：

ember generate route mapBy2

应用程序/路线/mapBy2.js


import Route from '@ember/routing/route'; 
import { classify, w } from '@ember/string'; 
import { mapBy } from '@ember/array'; 
  
export default class LanguagesRoute extends Route { 
    name = `Hindi Korean Marathi Telugu Portuguese 
        Turkish Bengali Spanish`; 
    num = `343.9 81.7 83.1 82.0 232.4 82.3 233.7 474`; 
  
    languages = []; 
  
    initLanguages() { 
        this.languages = []; 
        this.name = w(this.name); 
        this.num = w(this.num); 
        for (let i = 0; i < this.name.length; i++) { 
            let obj = new Object(); 
            obj['name'] = classify(this.name[i]); 
            obj['num'] = this.num[i]; 
            this.languages.pushObject(obj); 
        } 
    } 
    temp1; 
    convert(string) { 
        this.item = string.split(",").map((item) =>  
            item.trim()); 
        return this.item; 
    } 
  
    model() { 
        this.initLanguages(); 
        return this.languages; 
    } 
    setupController(controller, model) { 
        super.setupController(controller, model); 
        controller.set('languages', this.languages); 
        controller.set('temp1', this.temp1); 
        controller.set('convert', this.convert) 
    } 
}

应用程序/控制器/mapBy2.js


import Ember from 'ember'; 
import { mapBy } from '@ember/array'; 
  
export default Ember.Controller.extend({ 
    actions: { 
        get_Name() { 
            let ans = this.languages.mapBy('name'); 
            alert(ans.join('\n')); 
        }, 
        get_most() { 
            let temp = 0; 
            let tempItems = this.languages.map((item) => 
                temp < JSON.parse(item.num) ? temp =  
                item.name : temp); 
            alert(temp); 
  
        }, 
        remove() { 
            this.languages.popObject(); 
        }, 
        check_item(idx) { 
            let temp = this.languages.objectAt(JSON.parse(idx)); 
            alert(temp.name) 
        }, 
        check_items(idx) { 
            idx = this.convert(idx); 
            let temp = this.languages.objectsAt(idx); 
            let ans = temp.mapBy('name') 
            alert(ans.join('\n')) 
        }, 
  
    }, 
});

应用程序/模板/mapBy2.hbs


{{page-title "mapBy"}} 
<h2>Spoken Languages in the World</h2> 
<table style="border: 2px solid black;padding: 30px;"> 
    <tr> 
        <th>Language</th> 
        <th>Native Speakers (in Millions)</th> 
      </tr> 
      {{#each @model as |language|}} 
    <tr> 
        <td>{{language.name}}</td> 
          <td>{{language.num}}</td> 
    </tr> 
      {{/each}} 
</table> 
<br /><br /> 
<div> 
    <label>Enter index: </label> 
      {{input value=this.temp}} 
</div> 
<input 
    type="button"
      id="increase-pocket-money"
      value="Get Language at Index"
      {{action "check_item" this.temp}} 
/> 
<br /><br /> 
<div> 
    <label>Enter indexs: </label> 
      {{input value=this.temp2}} 
</div> 
<input 
    type="button"
      id="check-atIndex"
      value="Check at indexes"
      {{action "check_items" this.temp2}} 
/> 
<br /> 
<br /> 
<div> 
    <input 
        type="button"
        id="check-fruit"
        value="Check Most speaking Language"
        {{action "get_most"}} 
      /> 
</div> 
<br /> 
<div> 
    <input 
        type="button"
        id="remove-item"
        value="Remove Last Element"
        {{action "remove"}} 
      /> 
</div> 
<br /> 
<div> 
    <input 
        type="button"
        id="show-lang"
        value="Show Language"
        {{action "get_Name"}} 
      /> 
</div> 
{{outlet}}

输出：访问 localhost:4200/mapBy2 查看输出

Ember.js ArrayProxy mapBy 方法

参考：https://api.emberjs.com/ember/4.6/classes/ArrayProxy/methods/mapBy?anchor=mapBy

相关用法

注：本文由纯净天空筛选整理自jeemains0neet大神的英文原创作品 Ember.js ArrayProxy mapBy() 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。