How to check a JavaScript Object is a DOM Object ?

Prerequisite: DOM (Document object model), Instanceof Operator

DOM (Document Object Model): Document Object Model is a hierarchical representation of HTML and XML documents in a format that is easier to interpret in terms of programming. It makes manipulation of tags, elements, attributes, and classes by interpreting its structure in the form of a tree-like model consisting of nodes.

Element: In HTML DOM, Element is the general base class for all objects. An Element object represents all HTML elements.

Approach: In order to check whether a JavaScript object is a DOM object, we need to check whether the given JS object is of Element type Object. In order to check this, we will use instanceof operator. The instanceof operator returns a boolean value which specifies whether or not an object is an instance of a given Class.

Syntax:

Object instanceof ObjectType

Parameters:

  • Object: It stores the Object which need to be tested.
  • ObjectType: It stores the Object Type to be tested against.

Example:

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<!DOCTYPE HTML> 
<html
  
<head
    <title>
        How to check a JavaScript 
        Object is a DOM Object ?
    </title>
</head>
  
<body>
    <div id="div1"></div
    <div id="nonElem"></div
  
    <script>
        // Function to check the object
        // id DOM object or not
        function isDOM(Obj) {
              
             // Function that checks whether 
             // object is of type Element
            return Obj instanceof Element;
        }
      
        // Set all elements into HTML
        var div = document.getElementById('div1');
        var nonElem = document.getElementById('nonElem');
          
        // Creating a non-DOM Object 
        var x = 1; 
          
        // Checks against HTML elements and
        // non-HTML elements
        if (isDOM(div))
            div.innerHTML = "Div is detected as a DOM Object";
          
        if (!isDOM(x)) 
            nonElem.innerHTML = "x is detected as a non-DOM Object"; 
    </script>
</body>
  
</html>

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Output:

Div is detected as a DOM Object
x is detected as a non-DOM Object


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