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How to Work With Forms In JavaScript?: Step-By-Step Process with REAL-TIME Examples

Last updated on 04th Nov 2022, Artciles, Blog

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Pavni Krish (Senior QA Engineer )

Pavni Krish is an Senior QA Engineer manual testing with 8+ years of experience and she has skills in TestLodge, Zephyr, TestLink, Trello, Jira, Basecamp, Sauce Labs, Browser Shots.

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    • In this article you will learn:
    • 1.Introduction.
    • 2.What are forms in a JavaScript?
    • 3.How to Create a form using a JavaScript?
    • 4.JavaScript.
    • 5.JavaScript Form Validation.
    • 6.Data Validation.
    • 7.HTML Constraint Validation.
    • 8.Constraint Validation HTML Input Attributes.
    • 9.Conclusion.


JavaScript serves the wide range of functionalities, for example, can create a web and mobile applications using a JavaScript, JavaScript assists us in creating special effects, etc.Another useful feature of a JavaScript is that it helps us to enhance HTML forms.Can create a forms using the tag however, JavaScript can be used for the form processing, form validation, etc.JavaScript allows us process forms without calling/invoking the server.JavaScript offers a multiple properties and methods that are used to work with a forms. For example, can use the getElementById() method to read different HTML elements, using innerHTML property can set the form’s content and so on.

What are the forms in JavaScript?

  • A form is the container/holder that can hold several elements.
  • In a JavaScript the concept of forms is used to collect the user’s input using different elements like input fields, buttons, labels, fieldsets, text fields, and so on.
  • JavaScript can be used to interact with forms to validate the forms to process forms etc.

How to Create form using a JavaScript?

Let’s consider a below-given example to understand how to create form using a JavaScript:


Afterward created a form using a <"form"> tag and within form tag and created two input fields and a button.


HTML form validation can done by JavaScript:

  • In a JavaScript file i.e. form.js, can utilized the method to read the HTML elements.
  • Next, utilized innerHTML property to set a name and element.
  • On successful execution of program.
Forms in a JavaScript

JavaScript Form Validation:

  • HTML form validation can be a done by the JavaScript.
  • If a form field (fname) is empty, a function alerts message, and returns a false, to prevent form from being submitted.
  • An Automatic HTML Form Validation.
  • HTML form validation can be performed an automatically by a browser.
  • If form field (fname) is empty, the required attribute prevents this form from being be submitted.
  • A JavaScript Can Validate a Numeric Input.
  • A JavaScript is often used to validate a numeric input.

Data Validation:

Data validation is a process of ensuring that user input is be clean, correct, and useful.Typical validation tasks are be :

  • Has user filled in all the required fields?
  • Has user entered valid date?
  • Has user entered text in numeric field?
  • Most often a purpose of data validation is to ensure that correct user input.
  • Validation can be explained by many various methods and deployed in many various ways.

Server side validation: is performed by a web server after an input has been sent to a server.

Client side validation: is performed by a web browser before an input is sent to the web server.

HTML Constraint Validation:

HTML5 introduced new HTML validation concept are called a constraint validation.HTML constraint validation is based on:

  • A Constraint validation HTML Input Attributes.
  • A Constraint validation CSS Pseudo Selectors.
  • A Constraint validation DOM Properties and Methods.
JavaScript Form Validation

Constraint Validation HTML Input Attributes:

    Disabled Specifies that an input element should be a disabled.
    Max Specifies a maximum value of an input element.
    Min Specifies a minimum value of input element.
    Pattern Specifies a value pattern of input element.
    Required Specifies that a input field requires the element.
    Type Specifies a type of an input element.


In JavaScript a forms are used to collect user’s input using various elements like input fields, check boxes, buttons, text fields, and so on. JavaScript makes it possible to process a forms without calling the server.A JavaScript provides several properties and methods to work with forms like a getElementById() method to read different HTML elements, the innerHTML property to set a form’s content and so on.This write-up offers the basic understanding of JavaScript forms with help of a suitable examples.

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