Angular2 How to Handle null value in .find methode

Question

Here i wrote simple .find method its finding my data well but if that record is not available then its displying 1st Record

public _pagedItems : any;
    someval(value){
     if(value.length>=5){
        this._pagedItems= this.allItems.find(e=>e.uniqueid = value);
        this.pagedItems=[];
        this.pagedItems.push(this._pagedItems);

      }

if my uniquId is not avaible then its should display Nodata OR Null

Answer 1

Here is an example for handle null and undefined and return no data like

Your code is looking wrong. Your are code using (=) symbol. So change (==).

The difference between = and == (=) equal symbol is assigning value (==) symbol is comparing a value

For more proper example here,

public _pagedItems : any[]=[];
    someval(value:string){

    if(!this.isObjNull(value) && !this.isObjNull(this.allItems) && this.allItems.length>0){

     if(value.length>=5){
          if(this.allItems.find(e=>e.uniqueid ==value)){
               //you need one data use find
               this._pagedItems=this.allItems.find(e=>e.uniqueid == value);

              //you need multiple data use filter
              this._pagedItems = this.allItems.filter(e=>e.uniqueid == value);
          }
         //here Iam logged final variable 
         console.log("Final Paged Items",this._pagedItems);
      }
}
}

//here is the method check null and undefined.
isObjNull(data){
       If(data!=null && data!=undefined){
           return true:
       }else{
            return false;
       }
}

You can handle html part like this

<ng-container *ngIf="_pagedItems; else noData">
    <ng-container *ngIf="_pagedItems.length>0; else noData">
        <!--   do you logic here.like *ngFor -->
    </ng-container>
</ng-container>

<ng-template #noData>
     <p>No data found</p>
</ng-template>

That's all let try this once. If any error please let me know.

Note:- here Iam used sample variable please replace your actual variable.

For comparison related more thing visit here. Difference between == and === in JavaScript