JavaScript Form Validation Web application

Set up a basic html form with email, password, and username inputs, each with a hidden error span, and validate with JavaScript to show messages and enforce required fields.

Learn to make a web form interactive by listening for the form submit event, prevent default submission, run validation, and outline basic input styling to show errors.

Learn to gather all input values by selecting inputs, looping with for each, and building a data object mapping each input name to its value for form submission and validation.

validate required fields by checking string length and displaying error messages via addError, using a required fields array to target inputs and plan for email and password validations.

Build and test a JavaScript email validation using regular expressions, identify the email input, validate against a pattern, display an error for invalid emails, and gate form submission.

validate a password with a new regular expression, test for digits and both letter cases, enforce three to eight character length, and hide errors until the form submits.

Test the form validation by entering a valid username and email, and a password that meets the 3–8 character alphanumeric rule. Submit the form with JavaScript for completion.

Review a dynamic javascript form validation app, building inputs, preventing default submission, validating email and password with regex, handling errors, and assembling a data object for submission.

Compare how JavaScript uses == and === to evaluate numbers, strings, and arrays, with attention to false values like null, undefined, and empty string.