Invalid regular expression error in angular directive - regex

Question

Condition:
Contents can only contain characters from the following set:
a b c d e f g h i j k l m n o p q r s t u v w x y z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
0 1 2 3 4 5 6 7 8 9
/ - ? : ( ) . , ' +
• Contents may NOT begin with ‘/’
• Contents may NOT contain ‘//’
export function directDebitValidator(nameRe: RegExp): ValidatorFn {
return (control: AbstractControl): { [key: string]: any } | null => {
const directDebitID = nameRe.test(control.value);
return directDebitID ? { 'directDebit': { value: control.value } } : null;
};
}
#Directive({
selector: '[directDebit]',
providers: [{ provide: NG_VALIDATORS, useExisting: DirectDebitValidatorDirective, multi: true }]
})
export class DirectDebitValidatorDirective {
validate(control: AbstractControl): { [key: string]: any } | null {
return control.value ? directDebitValidator(new RegExp("^(? !.* [\/]{2})[a-zA-Z0-9-?:().,'+]+([a-zA-Z0-9\/-?:().,'+])*$"))(control)
: null;
}
}

Answer 1

There are a couple of issues:
There cannot be spaces in the lookahead definition
The [/-?] creates a range, the - must be escaped or placed at the start/end of the character class.
You may use a / unescaped in the constructor notation since no delimiters are being used there.
So, you may use
directDebitValidator(new RegExp("^(?!.*/{2})[a-zA-Z0-9?:().,'+-][a-zA-Z0-9/?:().,'+-]*$"))
Or, using a regex literal notation:
directDebitValidator(/^(?!.*\/{2})[a-zA-Z0-9?:().,'+-][a-zA-Z0-9\/?:().,'+-]*$/)
See the regex demo.