What exactly is the difference between ?. and !. in Angular?

Question

I've got the next line of code in my html template file:


    <span *ngIf="!signupForm.get('email')!.valid && signupForm.get('email')?.touched">

The 1st condition of the if has !. and the 2nd condition has ?. .

Both works just fine and when I don't use ? or ! it gives me the error: Object is possibly 'null'.

So does it really matter which one I use?

Does this answer your question? [Safe navigation operator (?.) or (!.) and null property paths](https://stackoverflow.com/questions/40238144/safe-navigation-operator-or-and-null-property-paths) — jeremy-denis, Oct 26 '22 at 11:58

score 2 · Answer 1 · answered Oct 26 '22 at 12:01

2

!. is TypeScript's null assertion operator, which asserts that the programmer knows the value to be not null, and asks typescript to believe the programmer. Should the value be null anyway, you'll get an exception.

?. is EcmaScript's optional chaining, which will access the property if the base is defined, or return undefined otherwise.

answered Oct 26 '22 at 12:01

meriton

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So does it matter which one I use in the given example? – DJ Freeman Oct 26 '22 at 12:24
Of course it matter! if you have *let yourUser: User = null;* if you call *yourUser!.name //throw error* instead *youUser?.name //undefined* – Luca Angrisani Oct 26 '22 at 13:54

What exactly is the difference between ?. and !. in Angular?

1 Answers1