how to distinguish Object type from Array type in Typescript

Question

how to check a type of an Object or of an Array?

I'm trying to add an Object (and add only if it's Object) to some Array.

//1. should add this OBJECT to the array
var objToAdd11 : Object = {name: 'Zack', age: 24};
this.addObject(objToAdd11);

//2. should throw errorbecause this is ARRAY, and we need only OBJECTS
var objToAdd22 : Array  = [{name: 'Zack', age: 24}];
this.addObject(objToAdd22);

public  addObject(obj: any) : void {
   /*I need to check is obj parameter OBJECT OR ARRAY*/
   var myArray : Array = [1, "a", 3];

   function () {
       myArray.push(obj);
   }

   var newMyArray : Array = myArray;
}

Jayakrishnan · Accepted Answer · 2017-05-26 12:30:01Z

2

You can use Array.isArray() to check if it's an array otherwise add it

var objToAdd11 : Object = {name: 'Zack', age: 24};
this.addObject(objToAdd11);

//2. should throw errorbecause this is ARRAY, and we need only OBJECTS
var objToAdd22 : Array  = [{name: 'Zack', age: 24}];
this.addObject(objToAdd22);

if(!Array.isArray(objToAdd11)){
 //add to list
}

Please check https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray?v=example

Hope it helps!!

answered May 26, 2017 at 12:30

Jayakrishnan

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Tushar Shukla · Accepted Answer · 2017-10-31 07:43:40Z

0

You can check for object by Object.keys(obj).length > 0 && obj.constructor === Object. Hope it helps.

//1. should add this OBJECT to the array
var objToAdd11: Object = {name: 'Zack', age: 24};
this.addObject(objToAdd11);

//2. should throw errorbecause this is ARRAY, and we need only OBJECTS
var objToAdd22: Array  = [{name: 'Zack', age: 24}];
this.addObject(objToAdd22);

public  addObject(obj: any) : void {
   /*I need to check if obj parameter is OBJECT OR ARRAY*/
   var myArray: Array = [1, "a", 3];

   if(Object.keys(obj).length > 0 && obj.constructor === Object) {
      myArray.push(obj);
   } else {
      console.error("Obj is not an Object");
   }

   var newMyArray: Array = myArray;
}

edited Oct 31, 2017 at 7:43

answered May 26, 2017 at 12:25

Tushar Shukla

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