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:
<!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 > |
Output:
Div is detected as a DOM Object x is detected as a non-DOM Object
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