1. Introduction

This tutorial focuses on two-way data binding, a powerful feature in Angular that allows you to keep the model and the view in sync. The goal is to understand and implement two-way data binding using the ngModel directive.

By the end of this tutorial, you will learn:
- The concept of two-way data binding
- How to implement two-way data binding using the ngModel directive
- Best practices for using two-way data binding

Prerequisites:
- Basic knowledge of Angular
- Basic understanding of TypeScript

2. Step-by-Step Guide

Two-way data binding is a mechanism that binds the model (component's property) and the view (DOM element) together. In other words, when we change something in our model, the view reflects it and vice-versa.

Angular provides a directive named ngModel for achieving two-way data binding. This directive is a part of FormsModule, so make sure to import it in your module.

Best practices:
- Use two-way data binding sparingly as it can lead to performance issues.
- Prefer one-way data binding wherever possible.

3. Code Examples

Here's a simple example of two-way data binding in Angular.

app.module.ts

import { FormsModule } from '@angular/forms';
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

@NgModule({
  declarations: [AppComponent],
  imports: [BrowserModule, FormsModule],
  providers: [],
  bootstrap: [AppComponent],
})
export class AppModule {}

app.component.html

<input [(ngModel)]="name" placeholder="name">
<p>Hello, {{name}}!</p>

app.component.ts

import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  name = '';
}

In this example, we first import FormsModule in our module. In our component's template, we bind the 'name' property to the input field using [(ngModel)]. When we type something in the input field, the 'name' property gets updated, and we see the updated name in our greeting message.

4. Summary

In this tutorial, we've learned how to use the ngModel directive for two-way data binding in Angular. We've seen how changes in the model or the view are reflected on the other side instantly.

As next steps, you can explore more about forms in Angular and how to handle form submissions.

Further reading:
- Angular Forms Documentation
- Two-Way Data Binding in Angular

5. Practice Exercises

Below are some practice exercises to reinforce your understanding:

1. Create a form with two fields: 'firstName' and 'lastName'. Display a full name in a paragraph that updates in real-time as you type in the input fields.
2. Create a checkbox that hides or shows a paragraph based on its state, using two-way data binding.

Solutions

1. Solution for Exercise 1:

<input [(ngModel)]="firstName" placeholder="First Name">
<input [(ngModel)]="lastName" placeholder="Last Name">
<p>Hello, {{firstName}} {{lastName}}!</p>

1. Solution for Exercise 2:

<input type="checkbox" [(ngModel)]="isChecked"> Show Paragraph
<p *ngIf="isChecked">This is a paragraph.</p>

These exercises should help you get a good grasp on two-way data binding. Try modifying these exercises or creating your own for further practice.