HTML DOM is used to access the elements of html document and make change them. DOM stands for Data Object Model. When a web page is loaded, the browser creates a DOM of the page. JavaScript can change all the HTML elements and css attributes in the page. DOM is a W3 Standard. It defines…

In JavaScript we defined a function using function keyword. Declaration of Function The following syntax will define the functions declaration : Example : OUTPUT : This example calls a function which performs a calculation, and returns the result:

Constraint Validation DOM Methods There are two methods : 1. checkValidity() 2. setCustomValidity() OUTPUT : Enter a number and click OK: OK If the number is less than 200 or greater than 400, an error message will be displayed.

JSON Stands for JavaScript Object Notation. JSON is a format for storing and transporting data means it is a data-interchange fornat. JSON is language independent. Exmaple : This JSON syntax defines a student object: an array of 3 student records (objects): Syntax Rules : Data is in name/value pairs Data is separated(,) by commas Curly…