极客教程Ember.js EmberArray对象的objectsAt()方法
Ember.js是一种开源的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是最广泛使用的前端应用框架之一。它被设计用来加快开发速度和提高生产力。目前，它被许多网站使用，包括Square、Discourse、Groupon、LinkedIn、Live Nation、Twitch和Chipotle。
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： 返回的项目。
安装和运行Ember.js的步骤：
步骤1： 要运行以下示例，您需要有一个Ember项目。要创建一个项目，您需要先安装ember-cli。在终端中写下以下代码：
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
开始服务器的方法是键入：
ember serve
示例1
输入以下代码生成此示例的路径：
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.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="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 以查看输出
示例2
输入以下代码以生成此示例的路线：
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
参考： https://api.emberjs.com/ember/4.4/classes/MutableArray/methods