Embeer.js Ember.NativeArray reduce()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。

reduce 方法用于将数组的值组合成单个值。此方法对于从数组收集摘要很有用。

用法:

reduce( callback, initialValue ) ;

参数：

callback：这是一个函数，将对数组的每个元素执行并返回结果。
initialValue：这是数组汇总的初始值。

返回值：此方法返回一个减少的值。

安装和运行 Ember.js 的步骤：

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 party

应用程序/路线/party.js

Javascript


import Route from '@ember/routing/route';
export default class PartyRoute extends Route {
    partyItems = [2, 3, 5, 6, 7, 8, 9, 2];
    ans;
    itemString;
    itemList;
    start;
    end;
    model() {
        return this.partyItems;
    }
    setupController(controller, model) {
        super.setupController(controller, model);
        controller.set('partyItems', this.partyItems);
        controller.set('ans', this.ans);
        controller.set('itemString', this.itemString);
        controller.set('itemList', this.itemList);
        controller.set('start', this.start);
        controller.set('end', this.end);
    }
}

应用程序/控制器/party.js

Javascript


import Ember from 'ember';
import {
    toArray,
    unshiftObject,
    unshiftObjects,
    removeAt,
    reduce,
} from '@ember/array';
export default Ember.Controller.extend({
    actions: {
        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);
        },
        sumItems() {
            let ans = this.partyItems.reduce(function
                (accum, curr) {
                return accum + curr;
            });
            alert('Sum of Array is ' + ans);
        },
    },
});

应用程序/模板/party.hbs

HTML


{{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 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>
    <input type="button" id="sum-items"
        value="Item sum" {{action "sumItems"}} />
</div>
{{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 fruits

应用程序/路线/fruits.js

Javascript


import Route from "@ember/routing/route";
import { } from "@ember/array";
export default class FruitsRoute extends Route {
    fruits = [
        {
            name: "Lady Finger",
            isFruit: false,
            color: "green",
        },
        {
            name: "Brinjal",
            isFruit: false,
            color: "purple",
        },
        {
            name: "Apple",
            isFruit: true,
            color: "red",
        },
        {
            name: "Grapes",
            isFruit: true,
            color: "green",
        },
        {
            name: "Mango",
            isFruit: true,
            color: "yellow",
        },
        {
            name: "Watermelon",
            isFruit: true,
            color: "red",
        },
        {
            name: "Orange",
            isFruit: true,
            color: "orange",
        },
    ];
    model() {
        return this.fruits;
    }
    setupController(controller, model) {
        super.setupController(controller, model);
        controller.set("fruits", this.fruits);
    }
}

应用程序/组件/fruits.js

Javascript


import Ember from "ember";
import { shiftObject, isAny, isEvery } from "@ember/array";
export default Ember.Controller.extend({
    actions: {
        removeFruit() {
            this.fruits.shiftObject();
        },
        anyFruit() {
            let Fruit_presence = this.fruits.reduce
                (function (accum, curr) {
                    return accum || curr['isFruit'];
                }, true);
            alert(`${Fruit_presence ? "Yes" : "No"}`);
        },
        allFruit() {
            let Fruit_presence = this.fruits.reduce
                (function (accum, curr) {
                    return accum && curr['isFruit'];
                }, true);
            alert(`${Fruit_presence ? "Yes" : "No"}`);
        },
    },
});

应用程序/模板/fruits.hbs

HTML


{{page-title "Fruits"}}
<h3>Here is a list of eatables: </h3>
<ul>
    {{#each @model as |eatable|}}
        <li style="color: {{eatable.color}}">
          {{eatable.name}}</li>
      {{/each}}
</ul>
<br /><br />
<input
    type="button"
      id="remove-eatable"
      value="Remove Eatable"
      {{action "removeEatable"}}
/>
<br /><br />
<input
    type="button"
      id="fruit-any"
      value="List Contains Any Fruit?"
      {{action "anyFruit"}}
/>
<br /><br />
<input
    type="button"
      id="fruit-all"
      value="List Contains Only Fruit?"
      {{action "allFruit"}}
/>
{{outlet}}

输出：访问 localhost:4200/fruits 查看输出

参考：https://api.emberjs.com/ember/4.6/classes/Ember.NativeArray/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 Ember.NativeArray reduce() 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。