function validate() {
var errMsg = "";
var result = true;
var fname = document.getElementById("fname").value;
if (!fname.match(/^[a-zA-Z]+$/)) {
errMsg += "Please enter your first name correctly.\n";
result = false;
}
if (errMsg) {
alert(errMsg);
}
if (result) {
function storeBooking(
fname
) {
sessionStorage.fname = fname;
}
function getBooking() {
if (sessionStorage.fname != undefined) {
document.getElementById("confirm_fname").textContent = sessionStorage.fname;
}
}
function prefillcard()
{
document.getElementById("fname").value = sessionStorage.fname;
}
window.addEventListener("DOMContentLoaded", prefillcard);
function init() {
var regForm = document.getElementById("regform");
regForm.onsubmit = validate;
}
<form action="apply.html" method="post" id="regform">
<label for="fname">First Name</label>
<input type="text" id="fname" name="firstname" placeholder="Your name.." required="required" maxlength="25" onkeypress="return (event.charCode > 64 && event.charCode < 91) || (event.charCode > 96 && event.charCode < 123) || (event.charCode==32)">
<input type="submit" value="Apply">
</form>
I've set up some code to auto-fill a form if the user had already filled the form in the same browser session and then revisited the form. The only problem is that there is a placeholder, which you need to delete before putting in an input, is there and I don't know how to get rid of it. "Undefined" comes up when you fill the form in the first time. How do I get rid of this?
Note: no jQuery or inline JavaScript.
To store values in session use
window.sessionStorage.setItem("Name", Value));
and to retrieve value from session use
window.sessionStorage.getItem("Name");
Sample code below
function prefillcard() {
if (window.sessionStorage.getItem("fname")) {
var fnm = window.sessionStorage.getItem("fname");
document.getElementById("fname").value = fnm;
}
}
and to set Session value use
var fnm = document.getElementById("fname").value;
window.sessionStorage.setItem("fname", fnm));
Related
I currently have a form with a few variables like username, password, and email which sends the data to a node.js server. Before sending the data, I have a few checks such as whether the inputs are valid and whether the email already exists in my file. The checking aspect of my code works, however the javascript function which I use to check returns before opening the file to check for duplicate emails. I feel that if I could somehow make the onsubmit function asynchronous, that would help.
Here is my code and the segment where I check for duplicate emails is near the end:
<html>
<body>
<form id='form' action="/signup.html" method="POST" onsubmit="return submitIt();">
<div style="text-align:center">
<label for="name">Full Name</label><br>
<input type="text" size="100" id="name" name="name" placeholder="Enter Your Full Name: "><br><br>
<label for="email">Email</label><br>
<input type="text" size="100" id="email" name="email" placeholder="Enter Your Email: "><br><br>
<label for="password">Password</label><br>
<input type="text" size="100" id="password" name="password" placeholder="Enter Your Password: "><br><br>
<button type="submit" id="submit">Submit</button>
</div>
</form>
</body>
<head>
<script type="text/javascript" src="http://code.jquery.com/jquery-latest.min.js"></script>
<script type="text/javascript">
var ret = true;
async function submitIt() {
let name = document.getElementById("name").value;
let email = document.getElementById("email").value;
let password = document.getElementById("password").value;
if (name == "" || name.length < 4) {
document.getElementById("name").value = "";
document.getElementById("name").placeholder = "Please enter a real name";
ret = false;
}
if (email == "" || email.length < 4) {
document.getElementById("email").value = "";
document.getElementById("email").placeholder = "Please enter a real email";
ret = false;
}
if (ret) {
let found = false;
for (let i = 0; i < email.length; i++) {
if (email[i] == '#') {
found = true;
}
}
if (!found) {
document.getElementById("email").value = "";
document.getElementById("email").placeholder = "Please enter a real email";
ret = false;
}
}
if (password.length < 5) {
document.getElementById("password").value = "";
document.getElementById("password").placeholder = "Password must be atleast 5 characters.";
ret = false;
}
await $.ajax({
type:"POST",
url:'/getUsers',
dataType: "text",
success: function(content) {
let contents = content.split('\n');
for (let i = 0; i < contents.length; i += 3) {
if (contents[i] == email) {
document.getElementById("email").value = "";
document.getElementById("email").placeholder = "Email already in use.";
ret = false;
}
}
}
});
return ret;
}
</script>
</head>
</html>
Any help would be greatly appreciated!
Have you tried moving onSumbmit call from form to the button?
const submitButton = document.getElementById(***)
submitButton.addEventListener('click', () => {your code})
Another way could be preventing default behavior of the submit form.
async function submitIt(event) {
event.preventDefault;
event.stopImmediatePropagation;
....your code....
}
I don't have access to a PC right now to check it, but one of the provided solutions should work. Cheers!
Guys I coded this in html and js. It is just simple three inputs, NAME, EMAIL and PASSWORD. I validated this simple form in javascript but it is not working as expected. I wanted that if I give wrong input to any one of three inputs, it should alert me "Please enter valid credentials." and if I give right input to all of these, It should alert me "Congrats! your form submitted.".
The validation which I gave to NAME field is if length of name is less than 1, it should return false, else true. The validation which I gave to PASSWORD field is same as NAME field and you can see the validation which I gave to all field in my code below. When I give wrong input to only one field, it is still showing me "Congrats! your form submitted."
It is not working as expected!
function ValidateForm(username, email, password)
{
if ((validateusername(username) || validateemail(email) || validatepassword(password))==false)
{
alert("Please Enter Valid Credentials.")
return false
}
else if ((validateusername(username))==true && (validateemail(email))==true && (validatepassword(password))==true)
{
alert("Congrats! your form submitted.")
}
}
function validateemail(email)
{
var x = email.value;
var atposition = x.indexOf("#");
var dotposition = x.lastIndexOf(".");
if (atposition<1 || dotposition<atposition+2 || dotposition+2>=x.length)
{
return false;
}
else
{
return true
}
}
function validateusername(username)
{
if (username.length<1)
{
return false;
}
else
{
return true
}
}
function validatepassword(password)
{
if (password.length<1)
{
return false;
}
else
{
return true
}
}
<form name="myForm">
<input type="text" name="Name" placeholder="Enter Name">
<input type="text" name="EmailAddr" placeholder="Enter Email">
<input type="text" name="Password" placeholder="Enter Password">
<button type="submit" onclick="ValidateForm(document.myForm.Name, document.myForm.EmailAddr, document.myForm.Password)">Submit</button>
</form>
The problem is your if statement condition.
(validateusername(username) || validateemail(email) || validatepassword(password))==false
is the same as
!validateusername(username) && !validateemail(email) && !validatepassword(password)
so you're saying it should only be considered invalid if all 3 validations fail.
This function can be cleaned up and fixed at the same time:
function ValidateForm(username, email, password)
{
if (!validateusername(username) || !validateemail(email) || !validatepassword(password)) {
alert("Please Enter Valid Credentials.")
return false
}
else {
alert("Congrats! your form submitted.")
}
}
That's all you need. If any one of those fails, then the form fails. Otherwise (else) it's fine. You don't need to re-check again.
One improvement you can make is to take as few arguments as necessary without impeding clarity. This function is called "validate form" so I'd expect the form to be the argument, like this:
ValidateForm(document.myForm)
Which is easy to accommodate internally:
function ValidateForm(form)
{
if (!validateusername(form.username) || !validateemail(form.email) || !validatepassword(form.password)) {
alert("Please Enter Valid Credentials.")
return false
}
else {
alert("Congrats! your form submitted.")
}
}
Which requires renaming your form fields to be consistent:
<input type="text" name="name" placeholder="Enter Name">
<input type="text" name="email" placeholder="Enter Email">
<input type="text" name="password" placeholder="Enter Password">
Tip: Try and have one and only one name for your things. Calling it variously Name or name is really counter-productive.
I would avoid inlining events.
Take a look.
document.myForm.addEventListener("submit", validateForm);
function validateForm(event) {
event.preventDefault();
const {
Name: username,
EmailAddr: email,
Password: password,
} = document.myForm;
if (!validateUsername(username) ||
!validateEmail(email) ||
!validatePassword(password)) {
console.log("Please Enter Valid Credentials.")
return;
}
console.log("Congrats! your form submitted.");
}
function validateEmail(emailField) {
const x = emailField.value;
const atposition = x.indexOf("#");
const dotposition = x.lastIndexOf(".");
if (atposition < 1 ||
dotposition < atposition + 2 ||
dotposition + 2 >= x.length) {
return false;
}
return true
}
function validateUsername(username) {
if (username.length < 1) {
return false;
}
return true;
}
function validatePassword(password) {
if (password.length < 1) {
return false;
}
return true;
}
<form name="myForm">
<input type="text" name="Name" placeholder="Enter Name">
<input type="text" name="EmailAddr" placeholder="Enter Email">
<input type="text" name="Password" placeholder="Enter Password">
<button type="submit">Submit</button>
</form>
Here is a bit of code I have sourced from w3schools which shows that whenever a name is over 10 characters, the page should add a bit of text, in this case, it should add on "hi", but instead, it removes everything from the page and goes onto a new page and only displays "hi". How can I resolve this?
<!DOCTYPE html>
<html>
<body>
<form action="/action_page.php" onsubmit="return myFunction()">
Name (max 10 characters): <input type="text" id="fname" size="20" name="fname"><br>
Age (from 1 to 100): <input type="text" id="age" size="20" name="age"><br>
E-mail: <input type="text" id="email" size="20" name="mail"><br><br>
<input type="submit" value="Submit">
</form>
<script>
function myFunction() {
var at = document.getElementById("email").value.indexOf("#");
var age = document.getElementById("age").value;
var fname = document.getElementById("fname").value;
submitOK = "true";
if (fname.length > 10) {
document.write("hi");
}
if (isNaN(age) || age < 1 || age > 100) {
alert("The age must be a number between 1 and 100");
submitOK = "false";
}
if (at == -1) {
alert("Not a valid e-mail!");
submitOK = "false";
}
if (submitOK == "false") {
return false;
}
}
</script>
</body>
</html>
Simply put, don't use document.write(). If you read the nice orange text at the top of the documentation, you'll see why:
Note: as document.write writes to the document stream, calling document.write on a closed (loaded) document automatically calls document.open, which will clear the document.
document.write() should only be used while a page is loading, to ouput while it's creating the webpage, and should not be used afterwards. Consider creating a div, and writing to there instead:
function myFunction() {
var at = document.getElementById("email").value.indexOf("#");
var age = document.getElementById("age").value;
var fname = document.getElementById("fname").value;
submitOK = "true";
if (fname.length > 10) {
document.getElementById('result').innerHTML = 'Fname is > 10!';
}
if (isNaN(age) || age < 1 || age > 100) {
alert("The age must be a number between 1 and 100");
submitOK = "false";
}
if (at == -1) {
alert("Not a valid e-mail!");
submitOK = "false";
}
if (submitOK == "false") {
return false;
} else {
alert('Submitted Successfully!');
return false; // Returning false here just for SO Code Snippet
}
}
<form action="/action_page.php" onsubmit="return myFunction()">
Name (max 10 characters): <input type="text" id="fname" size="20" name="fname"><br>
Age (from 1 to 100): <input type="text" id="age" size="20" name="age"><br>
E-mail: <input type="text" id="email" size="20" name="mail"><br><br>
<input type="submit" value="Submit">
<div id="result"></div>
</form>
Additionally, I notice you're setting submitOK = "true". Javascript does have booleans (See this also). Why not use that instead?
submitOK = true;
if (fname.length < 10) {
alert('Your name should be more than 10 characters');
submitOK = false;
}
if (submitOK) { // Same as "if (submitOK == true)"
//Good to go
}
First off, if this is against the rules, or frowned upon I'm very sorry and feel free to downvote/close. I'm desperately stuck.
I'm having trouble with an HTML page I wrote which is supposed to consist of inputs with certain requirements, adding div's to display error messages , and automatically update those error messages onblur. The assignment was made to test our javascript skills, and thus must be completely validated through javascript.
Here are a few of the guidelines...
validating the form for four separate things:
presence of required fields
equality of password fields
conformance to a password policy (one uppercase, one number, length > 7)
validity of the email address
When any one of these are violated, I should deactivate the form’s submit button so that it is not clickable and add a child "div" to the error-display containing an error message describing the situation.
The code seems correct to me, and works spontaneously, but i believe since javascript is looked at one line at a time it isn't displaying error messages correctly or even getting to certain parts of my code at all.
Here is my large chunk of javascript code, I am mainly looking for a way to break out of these if/else blocks that my code seems stuck in:
function formValidation() {
var form = document.getElementById('project-form');
var username = document.getElementById('username');
var name = document.getElementById('name');
var phone = document.getElementById('phone-number');
var email = document.getElementById('email');
var password = document.getElementById('password');
var passwordConfirmation = document.getElementById('password-confirmation');
var submit = document.getElementById('submit-btn');
var errorDisplay = document.getElementById('error-display');
var missingFieldBoolean = false;
var passwordMismatchBoolean = false;
var isUpper = false;
var isNumber = false;
var passwordLength = false;
var validEmail = false;
var createDiv = document.createElement("DIV");
var passwordConstraint, passwordConstraintError;
var mailformat = /^\w+([\.-]?\w+)*#\w+([\.-]?\w+)*(\.\w{2,3})+$/;
//Checks all fields for empty values and updates error div
if (username.value.length == 0 || name.value.length == 0 || email.value.length == 0 || password.value.length == 0 || passwordConfirmation.value.length == 0) {
missingField = errorDisplay.appendChild(createDiv);
missingField.setAttribute("id", "required-field-error");
missingFieldError = document.getElementById('required-field-error');
missingFieldError.innerHTML = "Missing Fields: ";
if (username.value.length == 0) {
missingFieldError.innerHTML += "Username - ";
}
if (name.value.length == 0) {
missingFieldError.innerHTML += "Full Name - ";
}
if (email.value.length == 0) {
missingFieldError.innerHTML += "Email - ";
}
if (password.value.length == 0) {
missingFieldError.innerHTML += "Password - ";
}
if (passwordConfirmation.value.length == 0) {
missingFieldError.innerHTML += "Password Confirmation - ";
}
} else {
errorDisplay.removeChild(missingFieldError);
missingFieldBoolean = true;
}
//Checks password vs password confirmation to see if they match, else updates error div
if (password.value != passwordConfirmation.value) {
passwordMismatch = errorDisplay.appendChild(createDiv);
passwordMismatch.setAttribute("id", "password-mismatch-error");
passwordMismatchError = document.getElementById('password-mismatch-error');
passwordMismatchError.innerHTML = "The Password and Password Confirmation do not match. Please re-enter.";
} else {
errorDisplay.removeChild(passwordMismatchError);
passwordMismatchBoolean = true;
}
//for loop to iterate through password to check for required characters, else updates error div
for (var index = 0; index < password.value.length; index++) {
if (password.value.charAt(index) == password.value.charAt(index).toUpperCase) {
isUpper = true;
}
if ("0123456789".indexOf(password.value.charAt(index)) > -1) {
isNumber = true;
}
if (password.value.length > 7) {
passwordLength = true;
} else {
passwordConstraint = errorDisplay.appendChild(createDiv);
passwordConstraint.setAttribute("id", "password-constraint-error");
passwordConstraintError = document.getElementById('password-constraint-error');
passwordConstraintError.innerHTML = "The Password must be 8 characters long, with one uppercase letter and one number. ";
}
}
//checks if password constraints are met and removes div if true
if (isUpper && isNumber && passwordLength) {
errorDisplay.removeChild(passwordConstraintError);
}
//checks email, if invalid it adds error div, else it removes the div ***NOT WORKING***
if (!(mailformat.test(email.value))) {
invalidEmail = errorDisplay.appendChild(createDiv);
invalidEmail.setAttribute("id", "invalid-email-error");
invalidEmailError = document.getElementById('invalid-email-error');
invalidEmailError.innerHTML = "Please enter a valid email address.";
} else {
errorDisplay.removeChild(invalidEmailError);
validEmail = true;
}
//if all requirements are met and true, submit button becomes enabled ***NOT WORKING***
if (isUpper && isNumber && passwordLength && missingFieldBoolean && passwordMismatchBoolean && validEmail) {
submit.disabled = false;
}
}
<div id="error-display"></div>
<br>
<form id="project-form" action="/submit.php" method="get" onclick="formValidation()">
<label>Username:</label>
<input id="username" type="text" onblur="formValidation()" required>
<c>*</c>
<br>
<label>Full Name:</label>
<input id="name" type="text" onblur="formValidation()" required>
<c>*</c>
<br>
<label>Phone Number:</label>
<input id="phone-number" type="tel">
<br>
<label>Email:</label>
<input id="email" type="email" onblur="formValidation()" required>
<c>*</c>
<br>
<label>Password:</label>
<input id="password" type="password" required onblur="formValidation()">
<c>*</c>
<br>
<label>Confirm Password:</label>
<input id="password-confirmation" type="password" required onblur="formValidation()">
<c>*</c>
<br>
<br>
<input id="submit-btn" type="submit" value="Submit" disabled>
</form>
Thanks a lot in advance, and again sorry if i'm breaking the rules.
I would put all the inputs into an object instead, that way you could automatically iterate over the object.
const fieldValues = [
'username',
'name',
'phone-number',
'email',
'password',
'password-confirmation',
]
.reduce((fieldsSoFar, fieldName) => {
fieldsSoFar[fieldName] = document.getElementById(fieldName).value;
return fieldsSoFar;
}, {});
const missingFieldsStr =
Object.entries(fieldValues)
.filter(([, fieldValue]) => fieldValue.length === 0)
.map(([fieldName]) => {
const words = fieldName.split(' ');
const upperWords = words.map(word => word.slice(0, 1).toUpperCase() + word.slice(1))
return upperWords;
})
.join(', ');
if (missingFieldsStr) {
// display it
}
// skipping some lines...
const hasUpper = /[A-Z]/.test(fieldValues.password);
const hasNumber = /[0-9]/.test(fieldValues.password);
And so on.
Don't implicitly create global variables - strongly consider using a linter.
Only use innerHTML when you're deliberately using or inserting HTML markup (which can have security and encoding problems). When you're setting or retrieving text values, use textContent instead.
I need to validate my form using JavaScript because iPhone / Safari do not recognize the required attribute. I want individual error messages to appear below each empty input field.
My code works, but the individual error message does not disappear when the field is filled in. Also, I would like all messages to appear initially, for all empty fields (not one by one). I am very very new to JavaScript, sorry.
My HTML:
<form onsubmit="return validateForm()" method="post" action="form.php" name="english_registration_form" id="english_registration_form">
<input type="text" id="name" name="name" aria-describedby="name-format" required placeholder="Name">
<span class="error"><p id="name_error"></p></span>
<input type="email" id="email" name="email" required placeholder="Email">
<span class="error"><p id="email_error"></p></span>
<input type="tel" id="telephone" name="telephone" required placeholder="Telephone">
<span class="error"><p id="telephone_error"></p></span>
<button class="register_button" type="submit" value="submit">Register Now</button>
</form>
And my JavaScript:
<script>
function validateForm() {
var x = document.forms["english_registration_form"]["name"].value;
var y = document.forms["english_registration_form"]["email"].value;
var z = document.forms["english_registration_form"]["telephone"].value;
if (x == null || x == "") {
nameError = "Please enter your name";
document.getElementById("name_error").innerHTML = nameError;
return false;
}
else if (y == null || y == "") {
emailError = "Please enter your email";
document.getElementById("email_error").innerHTML = emailError;
return false;
}
else if (z == null || z == "") {
telephoneError = "Please enter your telephone";
document.getElementById("telephone_error").innerHTML = telephoneError;
return false;
}
else {return true;}
}
</script>
Thanks for your help.
Here is a solution that displays all relevant errors when the form is first submitted, and removes an error when the user modifies text in the relevant input element.
To get it to display all of the errors on first run, I used if statements instead of if else, and used a flag to determine whether the form should be submitted. To remove the warnings when the input is modified, I bound the onkeyup events of the inputs.
I ended up removing the required attributes on the inputs so that the demonstration will work in a modern browser that supports them.
Live Demo:
document.getElementById("english_registration_form").onsubmit = function () {
var x = document.forms["english_registration_form"]["name"].value;
var y = document.forms["english_registration_form"]["email"].value;
var z = document.forms["english_registration_form"]["telephone"].value;
var submit = true;
if (x == null || x == "") {
nameError = "Please enter your name";
document.getElementById("name_error").innerHTML = nameError;
submit = false;
}
if (y == null || y == "") {
emailError = "Please enter your email";
document.getElementById("email_error").innerHTML = emailError;
submit = false;
}
if (z == null || z == "") {
telephoneError = "Please enter your telephone";
document.getElementById("telephone_error").innerHTML = telephoneError;
submit = false;
}
return submit;
}
function removeWarning() {
document.getElementById(this.id + "_error").innerHTML = "";
}
document.getElementById("name").onkeyup = removeWarning;
document.getElementById("email").onkeyup = removeWarning;
document.getElementById("telephone").onkeyup = removeWarning;
<form method="post" action="form.php" name="english_registration_form" id="english_registration_form">
<input type="text" id="name" name="name" aria-describedby="name-format" placeholder="Name"> <span class="error"><p id="name_error"></p></span>
<input type="email" id="email" name="email" placeholder="Email"> <span class="error"><p id="email_error"></p></span>
<input type="tel" id="telephone" name="telephone" placeholder="Telephone"> <span class="error"><p id="telephone_error"></p></span>
<button class="register_button" type="submit" value="submit">Register Now</button>
</form>
JSFiddle Version: https://jsfiddle.net/xga2shec/
First of all, we change your function validateForm so it can handle multiple validations.
Then, we create a DOMContentLoaded event handler on the document, and we call the validateForm function, so we validate the field when the page is loaded.
And to finish, we create input event handlers on the inputs, so everytime someone change any data inside them, the form is validated again.
Take a look at the code commented, and see the working version in action!
function validateForm() {
var valid = true; // creates a boolean variable to return if the form's valid
if (!validateField(this, 'name')) // validates the name
valid = false;
if (!validateField(this, 'email')) // validates the email (look that we're not using else if)
valid = false;
if (!validateField(this, 'telephone')) // validates the telephone
valid = false;
return valid; // if all the fields are valid, this variable will be true
}
function validateField(context, fieldName) { // function to dynamically validates a field by its name
var field = document.forms['english_registration_form'][fieldName], // gets the field
msg = 'Please enter your ' + fieldName, // dynamic message
errorField = document.getElementById(fieldName + '_error'); // gets the error field
console.log(context);
// if the context is the form, it's because the Register Now button was clicked, if not, check the caller
if (context instanceof HTMLFormElement || context.id === fieldName)
errorField.innerHTML = (field.value === '') ? msg : '';
return field.value !== ''; // return if the field is fulfilled
}
document.addEventListener('DOMContentLoaded', function() { // when the DOM is ready
// add event handlers when changing the fields' value
document.getElementById('name').addEventListener('input', validateForm);
document.getElementById('email').addEventListener('input', validateForm);
document.getElementById('telephone').addEventListener('input', validateForm);
// add the event handler for the submit event
document.getElementById('english_registration_form').addEventListener('submit', validateForm);
});
<form method="post" action="form.php" name="english_registration_form" id="english_registration_form">
<input type="text" id="name" name="name" aria-describedby="name-format" required placeholder="Name">
<span class="error"><p id="name_error"></p></span>
<input type="email" id="email" name="email" required placeholder="Email">
<span class="error"><p id="email_error"></p></span>
<input type="tel" id="telephone" name="telephone" required placeholder="Telephone">
<span class="error"><p id="telephone_error"></p></span>
<button class="register_button" type="submit" value="submit">Register Now</button>
</form>
you have to use style.display="none" to hide error
and style.display="block" to show error
<script>
function validateForm() {
var x = document.forms["english_registration_form"]["name"].value;
var y = document.forms["english_registration_form"]["email"].value;
var z = document.forms["english_registration_form"]["telephone"].value;
if (x == null || x == "") {
nameError = "Please enter your name";
document.getElementById("name_error").style.display="block";
document.getElementById("name_error").innerHTML = nameError;
return false;
}
else if (x != null || x != "") {
nameError = "Please enter your name";
document.getElementById("name_error").style.display="none";
return false;
}
if (y == null || y == "") {
emailError = "Please enter your email";
document.getElementById("email_error").style.display="block";
document.getElementById("email_error").innerHTML = emailError;
return false;
}
else if (y != null || y != "") {
emailError = "Please enter your email";
document.getElementById("email_error").style.display="none";
return false;
}
if (z == null || z == "") {
telephoneError = "Please enter your telephone";
document.getElementById("telephone_error").style.display="block";
document.getElementById("telephone_error").innerHTML = telephoneError;
return false;
}
else if (z != null || z != "") {
telephoneError = "Please enter your telephone";
document.getElementById("telephone_error").style.display="none";
return false;
}
else {return true;}
}
</script>
function validateForm() {
var valid = true; // creates a boolean variable to return if the form's valid
if (!validateField(this, 'name')) // validates the name
valid = false;
if (!validateField(this, 'email')) // validates the email (look that we're not using else if)
valid = false;
if (!validateField(this, 'telephone')) // validates the telephone
valid = false;
return valid; // if all the fields are valid, this variable will be true
}
function validateField(context, fieldName) { // function to dynamically validates a field by its name
var field = document.forms['english_registration_form'][fieldName], // gets the field
msg = 'Please enter your ' + fieldName, // dynamic message
errorField = document.getElementById(fieldName + '_error'); // gets the error field
console.log(context);
// if the context is the form, it's because the Register Now button was clicked, if not, check the caller
if (context instanceof HTMLFormElement || context.id === fieldName)
errorField.innerHTML = (field.value === '') ? msg : '';
return field.value !== ''; // return if the field is fulfilled
}
document.addEventListener('DOMContentLoaded', function() { // when the DOM is ready
// add event handlers when changing the fields' value
document.getElementById('name').addEventListener('input', validateForm);
document.getElementById('email').addEventListener('input', validateForm);
document.getElementById('telephone').addEventListener('input', validateForm);
// add the event handler for the submit event
document.getElementById('english_registration_form').addEventListener('submit', validateForm);
});
<form method="post" action="form.php" name="english_registration_form" id="english_registration_form">
<input type="text" id="name" name="name" aria-describedby="name-format" required placeholder="Name">
<span class="error"><p id="name_error"></p></span>
<input type="email" id="email" name="email" required placeholder="Email">
<span class="error"><p id="email_error"></p></span>
<input type="tel" id="telephone" name="telephone" required placeholder="Telephone">
<span class="error"><p id="telephone_error"></p></span>
<button class="register_button" type="submit" value="submit">Register Now</button>
</form>