Skip to content
Related Articles

Related Articles

Improve Article

How to check if a value is object-like in JavaScript ?

  • Last Updated : 12 May, 2021

In JavaScript, objects are a collection of related data. It is also a container for name-value pairs. In JavaScript, we can check the type of value in many ways. Basically, we check if a value is object-like using typeof, instanceof, constructor, and Object.prototype.toString.call(k). All of the operators are used in some specific conditions.

typeof operator: This is used to identify the type of variable. It returns a variable type. It is the easiest way to check the type of the variable. It works for some variables, but it did not identify the exact type of variable.

Hey geek! The constant emerging technologies in the world of web development always keeps the excitement for this subject through the roof. But before you tackle the big projects, we suggest you start by learning the basics. Kickstart your web development journey by learning JS concepts with our JavaScript Course. Now at it's lowest price ever!

Conditions: It treated array, set, and null same as the object. typeof returns object for all of these. In the case of variable except three of this typeof is used.

  • Syntax: 
typeof VariableName; 
  • Example:

Javascript




<script>
  
  let k = {Name:'gfg',Country:'India'};
  let k0 = new Set()
  let k1 = [1,2,3];
  let k2 = "hello";
  let k3 = null ;
  let k4 = undefined;
  
  console.log( typeof k  )
  console.log( typeof k0  )
  console.log( typeof k1  )
  console.log( typeof k2  )
  console.log( typeof k3  )
  console.log( typeof k4  )
  
</script>

Output:



object
object 
object
string 
object
undefined

instanceof operator: This is used to check if any instance is made with a certain constructor or not. It returns true if it is made with constructor else returns false. It only works for those who are wrapped in regular object types.

Condition: It treats the array and sets the same as the object. So we can use instanceof operator for all values except these two.

  • Syntax:
Variable instaceof object;
  • Example:

Javascript




<script>
  
  let k = {Name:'gfg',Country:'India'};
  let k0 = new Set()
  let k1 = [1,2,3];
  let k2 = "hello";
  let k3 = null ;
  let k4 = undefined;
  
  console.log( k   instanceof Object)
  console.log( k0   instanceof Object)
  console.log( k1  instanceof Object)
  console.log( k2  instanceof Object)
  console.log( k3  instanceof Object)
  console.log( k4  instanceof Object)
  
</script>

Output:

True 
True 
True
false 
false 
false

constructor property: This is the property of the variable which points to the fundamental object constructor type of that object. We can check for those variables which have constructor property. 

Condition: The constructor method throw an error for variables not having constructor property. null and undefined don’t have constructor property, so it throws an error.

  • Syntax: 
Variable.constructor === Object 
  • Example:

Javascript




<script>
  
  let k = {Name:'gfg',Country:'India'};
  let k0 = new Set()
  let k1 = [1,2,3];
  let k2 = "hello";
  
  console.log( k.constructor === Object)
  console.log( k0.constructor === Object)
  console.log( k1.constructor === Object)
  console.log( k2.constructor === Object)
  
<script>

Output:

True 
false 
false 
false 



My Personal Notes arrow_drop_up
Recommended Articles
Page :