javascript - Search filter with regex stuck my search filter and It does work without refresh? -

i searching patient through search filter.it worked in simple case when search sabir\\ stuck , after removing searchtext sabir\\ not work.it doesn't generate request next time.how handle sabir\\ in angular2. in advance here code snippet url work , not work? work "http://172.16.1.101:8080/openmrs/ws/rest/v1/patient?q=sabir&v=full" not work "http://172.16.1.101:8080/openmrs/ws/rest/v1/patient?q=\\&v=full"

i using function handling url.

validurl(str):boolean     {        var pattern = new regexp('^(https?:\/\/)?'+ // protocol       '((([a-z\d]([a-z\d-]*[a-z\d])*)\.)+[a-z]{2,}|'+ // domain name       '((\d{1,3}\.){3}\d{1,3}))'+ // or ip (v4) address       '(\:\d+)?(\/[-a-z\d%_.~+]*)*'+ // port , path       '(\?[;&a-z\d%_.~+=-]*)?'+ // query string       '(\#[-a-z\d_]*)?$','i'); // fragment locater     if(!pattern.test(str))        {         return false;     }     else      {       return true;     }   } 

service method searchpatient

searchpatient(term: string): observable<patient[]> {     if (!term) {       return observable.of<patient[]>([]);     }     const search_patient_url = `${this.webapiurl}${this.methodname}?q=${term}&v=full`;     console.log(search_patient_url);     this.apputilityservice.validurl(search_patient_url);     console.log(search_patient_url);     return this.http.get(search_patient_url, this.options)       .map(response => response.json().results patient[])       .do(data => console.log('patients', data))       .catch(this.handleerror); 

}

and here component code handling search term.

search(terms: string): void {     this.searcherror = null;     if(terms.length <= 2)     {       this.patient_results = null;       return;     }     if(terms)       this.loading = true;     this.patient_search_terms.next(terms);   }    loading:boolean = false;    ngoninit(): void {       this.patient_search_terms       .debouncetime(300) // wait 300ms after each keystroke before considering term       .switchmap(term =>         {            /*if(!this.apputilityservice.validurl(term))           {             console.log("invalid url");             term = null;           }           */           return term   // switch new observable each time term changes         // return http search observable         ? this.patientservice.searchpatient(term)         // or observable of empty patients if there no search term         : observable.of(null)})       .catch(error => {         // todo: add real error handling         console.log(error);         this.loading = false;         return observable.of(null);       }).subscribe(res=>{         this.loading = false;         if(!res || res.length === 0)         {           this.searcherror = "no result found";           this.patient_results = null;           return;         }         this.searcherror = null;         this.patient_results = observable.of(res);       })       this.searchform.valuechanges.subscribe(data=>{       this.searchtext = data;       if(!this.searchtext || this.searchtext == "")         {           this.clearsearch();           return;         }       this.search(this.searchtext);     });    }   clearsearch():void   {     this.patient_results = null;           this.loading = false;     this.searcherror = null;     this.searchtext = null;   }    searchkeyup(event):void   {     if(!this.searchtext || this.searchtext == "")       this.clearsearch();   } }