I have this code:

this.form = fb.group({
        username: ['', Validators.compose([Validators.required])],
        fullName: ['', Validators.compose([Validators.required])],
        password: ['', Validators.compose([Validators.required])],
        confirmPassword: ['', Validators.required],
    }, {validator: matchingPasswords('password', 'confirmPassword')});

matchingPasswords:

export function matchingPasswords(passwordKey: string, passwordConfirmationKey: string) {
return (group: FormGroup) => {
    let password = group.controls[passwordKey];
    let passwordConfirmation = group.controls[passwordConfirmationKey];
    if (password.value !== passwordConfirmation.value) {
        return passwordConfirmation.setErrors({mismatchedPasswords: true})
    }
}

}

html:

<div class="form-group">
        <input [formControl]="confirmPassword" class="form-control checking-field" type="password">
        <span class="help-block text-danger" *ngIf="form.get('password').touched && form.get('password').hasError('required')">
</div>
<div class="form-group">
        <input class="custom-control-input checkbox-main" type="checkbox" [(ngModel)]="policyButtonValue" [ngModelOptions]="{standalone: true}" ngDefaultControl>
        <span class="custom-control-indicator"></span>
</div>

this is functional, and works perfectly, but I have a special use-case scenario that should be fixed.

1. click in the first password field.
2. fill up a password, eg.: "foo"
3. click in the confirm password field.
4. tpye in the same thing, eg.:"foo" till this point, no problems.
5. type something different into the confirm password field, eg: "foobar" (at this point, the validator shows that there is an error here)
6. click in the password field
7. type in the same thing that is in the password field: "foobar" and here, the confirm password field is still invalid, until the password field looses focus... is there a way, to force the matchingPassword validation run on keyup event, rather than how it works now?