极客教程Ember.js的Ember.NativeArray objectsAt()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是最常用的前端应用程序框架之一。它旨在加速开发并提高生产力。目前，许多网站都在使用它，包括Square、Discourse、Groupon、Linked In、Live Nation、Twitch和Chipotle等。
objectsAt()方法用于获取给定索引数组的项目。
语法：
objectsAt(indexes)
参数：
- indexes： 需要获取对象的索引。
返回值： 返回的条目。
安装和运行Ember.js的步骤：
步骤1： 要运行以下示例，您需要一个带有Ember项目的问题。要创建一个，您需要先安装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，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 = [
"Digital Camera",
"Jugs, cups & straws",
"Balloons",
"Scissors",
"Cold Drink",
"Table Confetti",
"Party Hats",
"Wine",
"Napkins",
"Party Plates",
"Speakers",
"Music System",
"Cups",
];
itemString;
itemList;
start;
end;
helper(itemString) {
this.itemList = itemString.split(",");
for (let i = 0; i < this.itemList.length; i++)
this.itemList[i] = this.itemList[i].trim();
return this.itemList;
}
model() {
return this.partyItems;
}
setupController(controller, model) {
this._super(controller, model);
controller.set("helper", this.helper);
controller.set("partyItems", this.partyItems);
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 {
objectsAt,
removeObject,
removeObjects,
slice,
reverseObjects,
setObjects,
reject,
} from "@ember/array";
export default Ember.Controller.extend({
actions: {
getItems(itemString) {
this.itemList = this.helper(itemString);
for (let i = 0; i < this.itemList.length; i++)
this.itemList[i] = parseInt(this.itemList[i]);
let tempItems =
this.partyItems.objectsAt(this.itemList);
let str = "";
for (let i = 0; i < tempItems.length; i++)
str += tempItems[i] + "\n";
alert(str);
},
removeItems(itemString) {
this.itemList = this.helper(itemString);
if (this.itemList.length == 1)
this.partyItems.removeObject(this.itemList[0]);
else this.partyItems.removeObjects(this.itemList);
this.set("itemString", "");
},
sliceItems(start, end) {
let tempItems = this.partyItems.slice(start, end);
let str = "";
for (let i = 0; i < tempItems.length; i++)
str += tempItems[i] + "\n";
alert(str);
},
reverseItems() {
this.set("partyItems",
this.partyItems.reverseObjects());
},
replaceItems(itemString) {
this.partyItems.setObjects(this.helper(itemString));
},
findMultiwordItems() {
let reqItem = this.partyItems.reject(
(item) => item.split(" ").toArray().length == 1
);
alert(reqItem);
},
},
});
app/template/party.js
{{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="remove-item"
value="Remove Items"
{{action "removeItems" 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="slice"
value="Slice"
{{action "sliceItems" this.start this.end}}
/>
</div>
<br /><br />
<div>
<label>Enter Indices: </label>
{{input value=this.itemString}}
</div>
<div>
<input
type="button"
id="get-item"
value="Get Items"
{{action "getItems" this.itemString}}
/>
</div>
<br /><br />
<div>
<label>Enter Items: </label>
{{input value=this.itemString}}
</div>
<div>
<input
type="button"
id="replace-item"
value="Replace Items"
{{action "replaceItems" this.itemString}}
/>
</div>
<br /><br />
<input
type="button"
id="reverse-items"
value="Reverse"
{{action "reverseItems"}}
/>
<br /><br />
<input
type="button"
id="find-items"
value="Find"
{{action "findMultiwordItems"}}
/>
{{outlet}}
输出： 访问 localhost:4200/party 查看输出结果
示例2： 输入以下代码以生成此示例的路径：
ember generate route movie
app/routes/movie.js
import Route from "@ember/routing/route";
export default class MovieRoute extends Route {
movies = [
"The Shawshank Redemption",
"The Godfather",
"The Dark Knight",
"Schindler's List",
"The Godfather Part II",
"12 Angry Men",
"Pulp Fiction ",
"Raging Bull",
"Parasite",
"Se7en",
"3 Idiots",
"Forrest Gump",
"The Green Mile",
];
itemString;
itemList;
helper(itemString) {
this.itemList = itemString.split(",");
for (let i = 0; i < this.itemList.length; i++)
this.itemList[i] = this.itemList[i].trim();
return this.itemList;
}
model() {
return this.movies;
}
setupController(controller, model) {
super.setupController(controller, model);
controller.set("helper", this.helper);
controller.set("movies", this.movies);
controller.set("itemString", this.itemString);
controller.set("itemList", this.itemList);
}
}
app/controllers/movie.js
import Ember from "ember";
import {
objectsAt,
removeObject,
removeObjects,
setObjects,
reject,
} from "@ember/array";
export default Ember.Controller.extend({
actions: {
getItems(itemString) {
this.itemList = this.helper(itemString);
for (let i = 0; i < this.itemList.length; i++)
this.itemList[i] = parseInt(this.itemList[i]);
let tempItems = this.movies.objectsAt(this.itemList);
let str = "";
for (let i = 0; i < tempItems.length; i++)
str += tempItems[i] + "\n";
alert(str);
},
removeItems(itemString) {
this.itemList = this.helper(itemString);
if (this.itemList.length == 1)
this.movies.removeObject(this.itemList[0]);
else this.movies.removeObjects(this.itemList);
this.set("itemString", "");
},
replaceItems(itemString) {
this.movies.setObjects(this.helper(itemString));
},
findSingleWordItems() {
let reqItem = this.movies.reject(
(item) => item.split(" ").toArray().length > 1
);
alert(reqItem);
},
},
});
app/template/movie.hbs
{{page-title "Movie"}}
<h3>Here is a list of Movies: </h3>
<ul>
{{#each @model as |movie|}}
<li>{{movie}}</li>
{{/each}}
</ul>
<br /><br />
<div>
<label>Enter Movies: </label>
{{input value=this.itemString}}
</div>
<div>
<input
type="button"
id="remove-item"
value="Remove Movie"
{{action "removeItems" this.itemString}}
/>
</div>
<br /><br />
<div>
<label>Enter Indices: </label>
{{input value=this.itemString}}
</div>
<div>
<input
type="button"
id="get-item"
value="Get Movies"
{{action "getItems" this.itemString}}
/>
</div>
<br /><br />
<div>
<label>Enter Movies: </label>
{{input value=this.itemString}}
</div>
<div>
<input
type="button"
id="replace-item"
value="Replace Movies"
{{action "replaceItems" this.itemString}}
/>
</div>
<br /><br />
<input
type="button"
id="find-items"
value="Find"
{{action "findSingleWordItems"}}
/>
{{outlet}}
输出: 访问 localhost:4200/movie 查看输出结果
参考： https://api.emberjs.com/ember/4.6/classes/Ember.NativeArray/methods