angulartypescriptstrictnullchecks

How to tell Typescript that *in this instance* a function's return type is never null

I'm trying to get typescript strictNullChecks working in an Angular 5 project.

I have a form:

this.signinForm = this.fb.group({
  emailAddress: ['', NGValidators.isEmail()],
  password: ['', Validators.required],
  rememberMe: false,
});

I can get the rememberMe control using this.signinForm.get('rememberMe'). The return of the FormGroup#get method however, is AbstractControl | null so typescript doesn't like this.signinForm.get('rememberMe').value (because it thinks this.signinForm.get('rememberMe') could be null).

Is it possible to tell typescript that, in this instance, the return of this.signinForm.get('rememberMe') is always AbstractControl and not AbstractControl | null?

Solution

  • Use the ! operator:

    this.signinForm.get('rememberMe')!.value