极客教程Ember.js MutableArray unshiftObject() 方法
Ember.js 是一个采用基于模型-视图-控制器（MVC）架构用于开发大型客户端Web应用程序的开源JavaScript框架。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生产效率。目前，许多网站都在使用它，包括Square、Discourse、Groupon、LinkedIn、Live Nation、Twitch和Chipotle。
unshiftObject() 方法用于将单个对象添加到数组的开头。
语法：
unshiftObject(obj)
参数:
- obj: 要添加的对象。
返回值: 新的数组。
要运行以下示例，您需要拥有一个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
现在你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
输入以下代码生成此示例的路由：
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',
];
item;
itemString;
itemList;
start;
end;
idx;
model() {
return this.partyItems;
}
setupController(controller, model) {
this._super(controller, model);
controller.set('partyItems', this.partyItems);
controller.set('item', this.item);
controller.set('itemString', this.itemString);
controller.set('itemList', this.itemList);
controller.set('start', this.start);
controller.set('end', this.end);
controller.set('idx', this.idx);
}
}
app/controllers/party.js
import Ember from 'ember';
import {
without, toArray, unshiftObject, unshiftObjects,
removeAt, objectAt, find, replace, uniq
}
from '@ember/array';
export default Ember.Controller.extend({
actions: {
withoutItem(item) {
console.log(item)
let tempItems;
tempItems = this.partyItems.without(item);
let str = '';
for (let i = 0; i < tempItems.length; i++)
str += tempItems[i] + '\n';
alert(str);
this.set('item', '');
},
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);
},
getObject(idx) {
alert(`The item at index {idx} is
{this.partyItems.objectAt(idx)}`);
},
findMultipleWordItems() {
let reqItem = this.partyItems.find((item) =>
item.split(' ').toArray().length > 1);
alert(reqItem);
},
replaceItem(itemString) {
this.itemList = itemString.split(',').toArray();
if (this.itemList.length > this.partyItems.length)
alert('Error');
this.partyItems.replace(0, this.itemList.length,
this.itemList);
},
getUniqueItems() {
let tempItems = this.partyItems.uniq();
let str = '';
for (let i = 0; i < tempItems.length; i++)
str += tempItems[i] + '\n';
alert(str);
this.set('item', '');
},
},
});
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 Item: </label>
{{input value=this.item}}
</div>
<div>
<input type="button" id="remove-item"
value="Remove Item"
{{action 'withoutItem' this.item}} />
</div>
<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>
<label>Enter Index: </label>
{{input value=this.idx}}
</div>
<div>
<input type="button" id="get-item"
value="Get Item"
{{action 'getObject' this.idx}} />
</div>
<br /><br />
<div>
<label>Enter Items: </label>
{{input value=this.itemString}}
</div>
<div>
<input type="button" id="replace-item"
value="Replace Items"
{{action 'replaceItem' this.itemString}} />
</div>
<br /><br />
<input type="button" id="get-multiword"
value="Get Multiword Items!"
{{action 'findMultipleWordItems' }} />
<br /><br />
<input type="button" id="get-unique"
value="Get Unique Items!"
{{action 'getUniqueItems' }} />
{{outlet}}
输出： 访问 localhost:4200/party 查看输出
示例2
输入以下代码以生成此示例的路由：
ember generate route notepad
app/routes/notepad.js
import Route from '@ember/routing/route';
export default class NotepadRoute extends Route {
items = [];
item;
model() {
return this.items;
}
setupController(controller, model) {
super.setupController(controller, model);
controller.set('items', this.items);
}
}
app/controllers/notepad.js
import Ember from 'ember';
import { pushObject } from '@ember/array';
export default Ember.Controller.extend({
actions: {
withoutItem(item) {
let tempItems;
tempItems = this.items.without(item);
let str = '';
for (let i = 0; i < tempItems.length; i++)
str += tempItems[i] + '\n';
alert(str);
this.set('item', '');
},
replaceItem(item) {
let itemList = item.split(',').toArray();
if (itemList.length > this.items.length)
alert('Error');
this.items.replace(0, itemList.length, itemList);
},
addItem(item) {
this.items.unshiftObject(item);
},
getUniqueItems() {
let tempItems = this.items.uniq();
let str = '';
for (let i = 0; i < tempItems.length; i++)
str += tempItems[i] + '\n';
alert(str);
this.set('item', '');
},
},
});
app/template/notepad.hbs
{{page-title "Notepad"}}
<h2>Notepad</h2>
<div>
<label>Enter Item: </label>
{{input value=this.item}}
</div>
<div>
<input type="button" id="add-item"
value="Add Item"
{{action 'addItem' this.item}} />
</div>
<br /><br />
<ul>
{{#each @model as |item|}}
<li>{{item}}</li>
{{/each}}
</ul>
<br /><br />
<div>
<label>Enter Item: </label>
{{input value=this.item}}
</div>
<div>
<input type="button" id="without-item"
value="Without Item"
{{action 'withoutItem' this.item}} />
</div>
<br /><br />
<div>
<label>Enter Item: </label>
{{input value=this.item}}
</div>
<div>
<input type="button" id="replace-item"
value="Replace Item"
{{action 'replaceItem' this.item}} />
</div>
<br /><br />
<input type="button" id="get-unique"
value="Get Unique Items!"
{{action 'getUniqueItems' }} />
{{outlet}}
输出： 访问localhost:4200/notepad以查看输出
参考文献： https://api.emberjs.com/ember/4.4/classes/MutableArray/methods