Ember.js Ember.NativeArray reduce() 方法
Ember.js 是一个开源的 JavaScript 框架,用于开发大型的客户端 Web 应用程序,基于模型-视图-控制器 (MVC) 架构。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工作效率。目前它被许多网站使用,包括 Square、Discourse、Groupon、Linked In、Live Nation、Twitch 和 Chipotle。
reduce 方法用于将数组的值合并为单个值。该方法对于从数组中收集摘要非常有用。
语法:
reduce( callback, initialValue ) ;
参数:
- callback :这是一个在数组的每个元素上执行的函数,并返回结果。
- initialValue :这是数组汇总的初始值。
返回值: 此方法返回一个经过缩减的值。
安装和运行 Ember.js 的步骤:
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,首先需要安装 ember-cli。在终端中输入以下代码:
npm install ember-cli
步骤2: 现在你可以通过输入以下代码来创建项目:
ember new <project-name> --lang en
启动服务器,请输入:
ember serve
示例1: 输入以下代码生成此示例的路线:
ember generate route party
app/routes/party.js
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);
}
}
app/controllers/party.js
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);
},
},
});
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 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: 在此示例中,输入以下代码生成路由:
ember generate route fruits
app/routes/fruits.js
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);
}
}
app/components/fruits.js
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"}`);
},
},
});
app/template/fruits.hbs
{{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
参考资料: https://api.emberjs.com/ember/4.6/classes/Ember.NativeArray/methods