ngOnChanges(changes: SimpleChanges){
 let questionnaireChange = changes['questionnaire'];
 if(questionnaireChange.previousValue.state && 
 questionnaireChange.currentValue.state !== questionnaireChange.previousValue.state){
 this.questionnaire = changes['questionnaire'].currentValue;
 this.setState();
 }
 }

class SimpleChange {
constructor(previousValue: any, currentValue: any, firstChange: boolean)
previousValue : any
currentValue : any
firstChange : boolean
isFirstChange() : boolean
}