import {Directive, Input, OnChanges, HostBinding} from '@angular/core';

@Directive({

selector: '[ccLogo]'

})

export class CreditcardDirective implements OnChanges {

constructor() { }

@ Input () cardNumber:Number;

@HostBinding('src') imageSource;

ngOnChanges() {

if (this.cardNumber) {

if (this.cardNumber.indexof('34','37')) {

return this.cardNumber.Americanexpress;

} else if (this.cardNumber.startsWith('4')) {

return this.cardNumber.VISA;

} else if (this.cardNumber.startsWith('5')) {

return this.cardNumber.MASTERCARD;

}

}

return this.cardNumber.UNKNOWN;

}

}

Output

{ "resource": "/c:/Users/MobileTOS/Bania/modulea/src/app/creditcard.directive.ts", "owner": "typescript", "code": "2339", "severity": 8, "message": "Property 'indexof' does not exist on type 'Number'.", "source": "ts", "startLineNumber": 13, "startColumn": 27, "endLineNumber": 13, "endColumn": 34 }

Please fix this code