MDN Web Docs
developer.mozilla.org › en-US › docs › Learn_web_development › Extensions › Forms › Form_validation
Client-side form validation - Learn web development | MDN
Here is a full example to show usage of HTML's built-in validation features. First, some HTML: ... <form> <p>Please complete all required (*) fields.</p> <fieldset> <legend>Do you have a driver's license?
W3Schools
w3schools.com › js › js_validation.asp
W3Schools.com
JS Examples JS HTML DOM JS HTML Input JS HTML Objects JS HTML Events JS Browser JS Editor JS Exercises JS Quiz JS Website JS Syllabus JS Study Plan JS Interview Prep JS Bootcamp JS Certificate JS Reference ... HTML form validation can be done by JavaScript.
HTML Form Validation is heavily underused
Tried, didn’t work properly in, you guessed it, Safari on iOS (issues when the field with the error wasn’t visible, it didn’t autoscroll), scrapped it for a custom library with much more flexible validation features More on reddit.com
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August 14, 2024HTML Form Validation is heavily underused
Nice article. Small suggestion: I'd add a section about always validating form data on server side, too, as all client side checks can be circumvented by a bad actor. More on reddit.com
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October 28, 2024v-on:click on submit with html form validation
use a v-on:submit on the form, this is run after the validation passes. (and you also support submitting though screen readers and pressing the enter key that way) More on reddit.com
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June 30, 2020JavaScript Form validation tutorial For beginners (** Link in 1st Comment)
It looks good overall, but you are missing a few accessibility measures:
-
The inputs should have the
requiredattribute. Plus if you are using your own inline errors, you should putnovalidateon the form. -
There should be dynamic focus management on the first invalid input.
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The inline error should be connected to the input with
aria-describedby. -
Bonus points if you use
role="alert"andaria-live="assertive"to immediately notify the screen reader user. -
This is opinionated: the inline error should be removed on
changeandfocusout. That will match the UI of default HTML5 form validation.
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August 15, 2020Videos
07:28
Form Validation Easy Using HTML And CSS Only - YouTube
28:43
Creating a Beautiful Form Validation Project with HTML, CSS ...
09:22
10 Form Validation Tips Every Web Developer SHOULD KNOW! - YouTube
11:53
Form Input Validation in HTML - YouTube
08:04
HTML Form Validation: The Ultimate Guide for Beginners - YouTube
16 HTML Form Validations | 2026
GeeksforGeeks
geeksforgeeks.org › html › how-to-validate-input-field-in-the-html-form
How To Validate Input Field In The HTML Form? - GeeksforGeeks
December 1, 2025 - A simple HTML form with various input fields to collect user data. First Name and Last Name: Text input fields with required validation and minimum character length.
The Art of Web
the-art-of-web.com › html › html5-form-validation
HTML: HTML5 Form Validation Examples
For inputs that are both required and 'valid' you can use the following: <style> input:required:valid { /* insert your own styles for valid form input */ } </style> Some of the articles below, particularly the first two, provide other style/scripting options and solutions for supporting older ...
The Odin Project
theodinproject.com › lessons › node-path-intermediate-html-and-css-form-validation
Form Validation | The Odin Project
In our example we are using the pattern validation to ensure a US zip code is in the correct format (5 numbers followed by an optional dash and 4 more numbers): See the Pen forms-pattern-basic-validation by TheOdinProject (@TheOdinProjectExamples) on CodePen. You don’t really need to deep dive into regex for this. With how complex regex can get, especially when the exact syntax can differ when you’re writing them for HTML attributes, JavaScript strings, JavaScript regex literals etc., in practice you’re better off searching for an established regex for your needs rather than trying to construct one yourself.
MDN Web Docs
developer.mozilla.org › en-US › docs › Web › HTML › Guides › Constraint_validation
Using HTML form validation and the Constraint Validation API - HTML | MDN
November 25, 2025 - HTML5 introduced new mechanisms for forms: it added new semantic types for the <input> element and constraint validation to ease the work of checking the form content on the client side. Basic, usual constraints can be checked, without the need for JavaScript, by setting new attributes; more complex constraints can be tested using the Constraint Validation API. For a basic introduction to these concepts, with examples...
Educative
educative.io › answers › form-validation-with-html-and-css
Form validation with HTML and CSS
Place the code in appropriate files and open the HTML file in a web browser. Following is an example of a form that allows users to input their name, email, and password. The form includes basic validation to ensure that the entered data is valid and meets certain criteria.
Bootstrap
getbootstrap.com › docs › 5.0 › forms › validation
Validation · Bootstrap v5.0
Here’s how form validation works with Bootstrap: HTML form validation is applied via CSS’s two pseudo-classes, :invalid and :valid.
W3Schools
w3schools.com › html › html_form_attributes.asp
HTML Input Attributes
The autocomplete attribute works with <form> and the following <input> types: text, search, url, tel, email, password, datepickers, range, and color. An HTML form with autocomplete on, and off for one input field:
DhiWise
dhiwise.com › post › html-form-validation-techniques-tips-and-tools
HTML Form Validation: Techniques, Tips, and Tools
July 10, 2024 - ... 1<!-- HTML for phone number input with validation --> 2<input type="tel" id="phone" name="phone" pattern="^\+1\s?\(\d{3}\)\s?\d{3}-\d{4}$" required title="Enter a phone number in the format: +1 (555) 123-4567"> 3
htmx
htmx.org › examples › inline-validation
htmx ~ Examples ~ Inline Validation
.error-message { color:red; } .error input { box-shadow: 0 0 3px #CC0000; } .valid input { box-shadow: 0 0 3px #36cc00; } To give better visual feedback. Below is a working demo of this example.
W3Schools
w3schools.com › php › php_form_validation.asp
PHP Form Validation
These pages will show how to process PHP forms with security in mind. Proper validation of form data is important to protect your form from hackers and spammers! The HTML form we will be working at in these chapters, contains various input fields: required and optional text fields, radio buttons, ...
WordPress
wordpress.org › support › topic › how-to-add-basic-javascript-form-validation-prior-to-processing-a-html-form
How to Add Basic JavaScript Form Validation Prior to Processing a HTML Form | WordPress.org
January 19, 2024 - This code provides basic client-side validation for your form. You can customize it further according to your specific requirements. ... @abretado1985: Note that depending on what “basic validation” you’re after, you may be able to do it in pure HTML without any JavaScript. For instance, I understand @dealtek response is only an example meant to be customized for your needs.
Coryrylan
coryrylan.com › blog › styling-html-form-validation-with-css
Styling HTML Form Validation with CSS
February 28, 2025 - In this example, we leverage the :has selector to target the fieldset element when it has a invalid form field. We then use the aria-live attribute to show a custom error message when the user has not entered a valid email address.
AlmaBetter
almabetter.com › bytes › tutorials › html › form-validation-in-html
Form Submission and Validation in HTML
Learn how to implement form validation and ensure accurate form submission.Explore HTML techniques for validating forms, handling errors optimizing user input.
OpenReplay
blog.openreplay.com › form-validation-with-html
Form Validation with HTML
September 30, 2022 - How to validate your form in HTML5? Using the form validation tag required, which makes the data in that field mandatory to enter, an example of form validation using the HTML5 validation attribute is provided below.
Udacity
udacity.com › blog › 2021 › 10 › javascript-html-form-validation-dotting-every-i.html
Javascript HTML Form Validation — Dotting Every I | Udacity
October 8, 2021 - Similarly, the following CSS pseudo-selectors can constrain input values: :disabled, :invalid, :optional, :required, :valid · Javascript HTML form validation requires two components: the HTML form that accepts inputs (constrained as specified above) and a Javascript function which performs validation above the built-in constraints.
LogRocket
blog.logrocket.com › home › when and how to choose html for form validation
When and how to choose HTML for form validation - LogRocket Blog
June 4, 2024 - HTML5 also introduced some new CSS selectors, including two new pseudo-classes — :valid and :invalid. These match any input whose value has passed or failed validation, respectively. For example, we can automatically mark invalid fields with a red border:
W3Resource
w3resource.com › javascript › form › javascript-form-validation.php
JavaScript : HTML Form Validation - w3resource
August 19, 2022 - ... If an HTML document contains more than one forms, they can be accessed as either by document.form_name where form_name is the value of the name attribute of the form element or by document.forms[i] where i is 0, 1,2,3....
Devchallenges
devchallenges.io › learn › 2-responsive-web › form-and-form-validation
HTML Forms & Validation: Step-by-Step Guide | devChallenges
Master HTML forms and validation: create secure, user-friendly forms with step-by-step guidance on input types, attributes, and JavaScript techniques.