ngModel for form binding in Angular - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is ngModel used for in Angular?

ngModel is used to create a two-way binding between form inputs and component data. It keeps the input and the data in sync automatically.

beginner

How do you enable two-way binding with ngModel in Angular templates?

Use the syntax [(ngModel)]="propertyName" on an input element to bind the input value to the component's propertyName and update it on user input.

beginner

What module must be imported to use ngModel in Angular?

<p>You must import <code>FormsModule</code> from <code>@angular/forms</code> in your Angular module to use <code>ngModel</code>.</p>

intermediate

What happens if you use ngModel without importing FormsModule?

Angular will throw an error because ngModel directive is not recognized without FormsModule imported.

intermediate

Explain the difference between one-way binding and two-way binding in Angular forms.

One-way binding updates the view from the component data only. Two-way binding with ngModel updates both the view and the component data automatically as the user types.

Which syntax correctly sets up two-way binding with ngModel?

A <code>(ngModel)="username"</code>

B <code>[ngModel]="username"</code>

C <code>[(ngModel)]="username"</code>

D <code>ngModel="username"</code>

Two-way binding requires the banana-in-a-box syntax: [(ngModel)].

What must you import to use ngModel in your Angular app?

A BrowserModule

B FormsModule

C HttpClientModule

D ReactiveFormsModule

FormsModule provides the ngModel directive for template-driven forms.

If you want to bind an input's value to a component property but only update the view when the property changes, which binding do you use?

A One-way binding with <code>[value]</code>

B Event binding with <code>(input)</code>

C Two-way binding with <code>[(ngModel)]</code>

D No binding

One-way binding updates the view from the component property only, using [value].

What does two-way binding with ngModel do when a user types in an input field?

A Does nothing automatically

B Updates the input field only

C Updates the component property only

D Updates both the input field and the component property

Two-way binding keeps the input and component property in sync automatically.

Which Angular directive is used for two-way data binding in template-driven forms?

A <code>ngModel</code>

B <code>ngFor</code>

C <code>ngClass</code>

D <code>ngIf</code>

ngModel is the directive for two-way binding in forms.

Describe how ngModel works for form input binding in Angular.

Think about how the input and data stay updated together.

Explain why importing FormsModule is necessary when using ngModel.

Consider what Angular needs to recognize ngModel.