Validate Individual Fields validationMessage — The validation message — an empty string when a field is valid. setCustomValidity(message) — Sets an error message for an invalid field. Pass an empty string when the field is valid or it remains invalid forever. checkValidity() — Returns true when the input is valid.

Form Submission: When you click “submit,” React checks for errors using the validateForm() function. If there are no errors, it logs the submitted data; if there are errors, it shows error messages.

// Create form var form = document. createElement('form'); // Create form inputs var inputName = document. createElement('input'); inputName. type = 'text'; inputName.name = 'userName'; inputName.