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📜  Angular 6-事件绑定

📅  最后修改于: 2020-10-28 05:25:31             🧑  作者: Mango

在本章中，我们将讨论事件绑定在Angular 6中的工作方式。当用户以键盘移动，鼠标单击或鼠标悬停的形式与应用程序交互时，它将生成一个事件。需要处理这些事件以执行某种操作。这是事件绑定出现的地方。

让我们考虑一个例子，以更好地理解这一点。

app.component.html




   

      Welcome to {{title}}.
   




 Months :
   






   
      Condition is valid.
   
   Condition is valid
   Condition is invalid

在app.component.html文件中，我们定义了一个按钮，并使用click事件向其中添加了一个函数。

以下是定义按钮并为其添加函数的语法。

(click)="myClickFunction($event)"

该函数在.ts文件中定义： app.component.ts

import { Component } from '@angular/core';
@Component({
   selector: 'app-root',
   templateUrl: './app.component.html',
   styleUrls: ['./app.component.css']
})
export class AppComponent {
   title = 'Angular 6 Project!';
   //array of months.
   months = ["January", "Feburary", "March", "April",
            "May", "June", "July", "August", "September",
            "October", "November", "December"];
   isavailable = true;
   myClickFunction(event) { 
      //just added console.log which will display the event details in browser on click of the button.
      alert("Button is clicked");
      console.log(event);
   }
}

单击按钮后，控件将转到函数myClickFunction ，将出现一个对话框，该对话框显示单击了Button ，如以下屏幕截图所示-

使用myClickFunction输出

现在让我们将change事件添加到下拉列表中。

以下代码行将帮助您将change事件添加到下拉列表中-




   

      Welcome to {{title}}.
   




 Months :
   






   
      Condition is valid.
   
   Condition is valid
   Condition is invalid

该函数在app.component.ts文件中声明-

import { Component } from '@angular/core';
@Component({
   selector: 'app-root',
   templateUrl: './app.component.html',
   styleUrls: ['./app.component.css']
})
export class AppComponent {
   title = 'Angular 6 Project!';
   //array of months.
   months = ["January", "Feburary", "March", "April",
            "May", "June", "July", "August", "September",
            "October", "November", "December"];
   isavailable = true;
   myClickFunction(event) {
      alert("Button is clicked");
      console.log(event);
   }
   changemonths(event) {
      console.log("Changed month from the Dropdown");
      console.log(event);
   }
}

控制台消息“从下拉菜单更改了月份”与事件一起显示在控制台中。

从下拉菜单更改月份

当下拉菜单中的值更改时，让我们在app.component.ts中添加警报消息，如下所示-

import { Component } from '@angular/core';
@Component({
   selector: 'app-root',
   templateUrl: './app.component.html',
   styleUrls: ['./app.component.css']
})
export class AppComponent {
   title = 'Angular 6 Project!';
   //array of months.
   months = ["January", "February", "March", "April",
            "May", "June", "July", "August", "September",
            "October", "November", "December"];
   
   isavailable = true;
   myClickFunction(event) { 
      //just added console.log which will display the event details in browser 
      on click of the button.
      alert("Button is clicked");
      console.log(event);
   }
   changemonths(event) {
      alert("Changed month from the Dropdown");
   }
}

更改下拉列表中的值时，将出现一个对话框，并显示以下消息-“下拉列表中的月份已更改”。

从下拉菜单2更改月份