How to make 'submit' button disabled?

in Angular 2.x.x , 4, 5 ...

<form #loginForm="ngForm">
    <input type="text" required> 
    <button  type="submit"  [disabled]="loginForm.form.invalid">Submit</button>
</form>

As seen in this Angular example, there is a way to disable a button until the whole form is valid:

<button type="submit" [disabled]="!ngForm.valid">Submit</button>