Template-driven forms are suitable for simple scenarios, and form state is processed through ngModel and instructions; responsive forms are suitable for complex controls, and models are built manually through FormControl and FormGroup; verification can be implemented through built-in rules or custom functions; performance-oriented, lazy loading, sharing state, abstract components, and patchValue are recommended.

Handling forms in Angular is not that complicated, but to really use them well, you still need to understand its working mechanism and best practices. Angular provides two main ways to handle forms: template-driven forms and responsive forms. Which method to choose depends on your project requirements and complexity.

Template-driven form: suitable for simple scenarios

If you only need to deal with some simple user input, such as login and registration, template-driven forms will be lighter and easier to get started.

This form binds data by using ngModel in the template, and automatically collects form status with instructions such as ngForm (such as touched, valid, etc.).

 <form #myForm="ngForm" (ngSubmit)="onSubmit(myForm)">
  <input name="email" ngModel required email />
  <button type="submit">Submit</button>
</form>

Here are a few key points to note:

• You must add name attribute to each input, otherwise it will not be tracked correctly.
• The form status can be obtained through myForm.form.status
• Verification rules are implemented through HTML5 native attributes, such as required and email

This method is quick to write, but is not suitable for complex business logic or dynamic form structures.

Responsive forms: More suitable for complex controls

When you need more control, such as dynamically adding fields, conditional verification, and nested form structures, you should use Reactive Forms .

Its core is to manually build form models in component classes through FormControl , FormGroup , and FormArray . The advantage of this is that it has clear structure and strong testability, making it suitable for large applications.

 this.myForm = new FormGroup({
  name: new FormControl('', Validators.required),
  emails: new FormArray([
    new FormControl('', Validators.email)
  ])
});

Then bind these controls in the template:

 <input [formControl]="myForm.get(&#39;name&#39;)" />
<div formArrayName="emails">
  <input *ngFor="let email of myForm.get(&#39;emails&#39;).controls; let i=index" 
         [formControlName]="i" />
</div>

Several practical suggestions:

• Combining multiple validators using Validators.compose()
• Use the change of valueChanges subscription value to perform real-time verification or linkage
• For a large number of duplicate fields, it can be encapsulated into independent components and passed into FormControl

Form verification skills: Don’t rely solely on interface feedback

No matter which form type it is, verification is a key link. In addition to basic built-in rules such as required and email, you can also customize the verification function.

For example, determine whether the two passwords are consistent:

 function matchPassword(control: AbstractControl): ValidationErrors | null {
  const pwd = control.get('password')?.value;
  const confirm = control.get('confirmPassword')?.value;
  return pwd === confirm ? null : { mismatch: true };
}

Then pass this function in as FormGroup validator .

In addition, remember to display error messages in time on the interface, such as:

 <div *ngIf="myForm.get(&#39;password&#39;).touched && myForm.get(&#39;password&#39;).invalid">
  Password cannot be empty</div>

Performance and Maintainability Tips

Although Angular forms are powerful, if used poorly, they may slow down performance or cause code confusion. Here are some tips that are easy to ignore:

• If there are many form items, try to avoid initializing all fields at once. You can gradually build them by lazy loading.
• When sharing form status among multiple components, consider using the service BehaviorSubject management
• For a large number of repeated form structures, it can be abstracted into a general component, receiving a FormGroup or FormControl via @Input
• Try to use patchValue instead of setValue to avoid errors due to missing fields

Basically that's it. Forms are a high-frequency scenario in front-end development. Angular provides good support. As long as the differences and applicable scenarios are understood clearly, it is still easy to use.

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