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Avoid user click submit button more than once?

I'm working on a asp.net MVC project. On one page, it has many controls and features. When user clicks 'submit' button, it will do many validations in the controller for the input. If something is not right, it will show the error on the page. Otherwise, will save the data in the database with a Guid, and go to the next page.
The problem is: the validation takes some time, user may accidentally click the submit button more than once which results in saving data to the database with the same Guid, which throws an error since Guid has to be unique for each data.
Is there a way to prevent user clicking more than once? We can not simply disable the button after click. If the validation has issue, then user can not submit again since the button is disabled.

You can disable the submit button until all the validation has been completed. Track a variable for each conditional that returns true when the validation for that section of the form is complete and then check each of these variables at the end to make sure each one is true. If they are all true set the submit.disabled to false.
NOTE: You can do this with each input as well, disabling each input until the previous input has been properly validated.
Below is a very rudimentary example of this logic.
const submit = document.getElementById('submit')
const fname = document.getElementById('fname')
const lname = document.getElementById('lname')
const email = document.getElementById('email')
const inputs = document.querySelectorAll('.input')
function emailIsValid(email) {
return /^[^\s#]+#[^\s#]+\.[^\s#]+$/.test(email)
}
function nameIsValid(name) {
return name.match(/^[A-Za-z]+$/)
}
function validate(fname, lname, email, submit) {
// the validation variables to check at end to set submit.disabled to false
let fnameCheck = false,
lnameCheck = false,
emailCheck = false;
// check first name field
if (fname.value !== '' && fname.value.length > 1 && nameIsValid(fname.value)) {
fname.style.background = 'lightgreen'
fname.previousSibling.previousSibling.style.background = 'green'
fnameCheck = true
} else {
// JIC they delete reset to false
fnameCheck = false
fname.style.background = 'pink'
}
if (lname.value !== '' && lname.value.length > 2 && nameIsValid(fname.value)) {
lnameCheck = true
lname.style.background = 'lightgreen'
} else {
lnameCheck = false
lname.style.background = 'pink'
}
if (emailIsValid(email.value)) {
emailCheck = true
email.style.background = 'lightgreen'
} else {
emailCheck = false
email.style.background = 'pink'
}
// log for visual inspection of check-variable values
console.log(lnameCheck, fnameCheck, emailCheck)
// make sure all check-variables are set to true
if (fnameCheck === true && lnameCheck === true && emailCheck === true) {
submit.disabled = false
}
}
// event listener for each input on input field run the validate function
// and pass in our inputs and submit button for manipulation.
inputs.forEach(input =>
input.addEventListener('input', () => validate(fname, lname, email, submit))
)
<form action="#">
<label for="fname">First name:</label><br>
<input type="text" id="fname" name="fname" class="input"><br>
<label for="lname">Last name:</label><br>
<input type="text" id="lname" name="lname" class="input"><br>
<label for="email">email:</label><br>
<input type="text" id="email" name="email" class="input"><br>
<input type="submit" id="submit" value="Submit" disabled>
</form>

Submit button clearing out form, and not displaying anything

I'm trying to create a fun little registration sheet to practice my validation. When I hit the submit button I have two issues. The first issue is my form keeps clearing every input field the moment I hit submit. I tried to use have my onclick = return false but this did nothing. The next issue I'm having is when I hit submit nothing happens at all. I'm not sure where I have messed up but if someone could point it out to me.
<!-- create a function to validate and pass information along -->
function Validation() {
<!-- declare variables -->
var ifErrors = false;
<!-- create the array to display error messages when cycled through -->
var ErrorMessage = new Array();
var myUserName = document.getElementById("txtUsername").value;
var myPassword = document.getElementById("txtPassword").value;
var myFirstName = document.getElementById("txtFirstName").value;
var myLastName = document.getElementById("txtLastName").value;
var myDateOfBirth = document.getElementById("txtDateOfBirth").value;
var myEmail = document.getElementById("txtEmail").value;
var myPhoneNumber = document.getElementById("txtPhoneNumber").value;
var LettersOnly = /^[a-z]+$/;
var DateOfBirthValidate = /^(0[1-9]|1[0-2])\/(0[1-9]|1\d|2\d|3[01])\/(19|20)\d{2}$/;
var Dates = new Date();
var DateSupplied = document.getElementById("txtDateOfBirth").value;
var PhoneNumberValidate = /^\([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/;
<!-- Begin validation -->
//validate for username being blank
if (myUserName = "")
{
ifErrors = true;
ErrorMessage.push('Username is required');
}
//validate for username not being 8 or more characters
if(myUserName.length < 8)
{
ifErrors = true;
ErrorMessage.push('Username must be 8 or more characters');
}
//validate for password being blank
if (myPassword == "")
{
ifErrors = true;
ErrorMessage.push('Password is required');
}
//validate for password not being 8 or more characters
if (myPassword.length < 8)
{
ifErrors = true;
ErrorMessage.push('Password must be 8 or more characters');
}
//validate for first name being blank
if (myFirstName == "")
{
ifErrors = true;
ErrorMessage.push('First name can not be blank');
}
//validate for last name being blank
if (myLastName == "")
{
ifErrors = true;
ErrorMessage.push('Last name can not be blank');
}
//validate for date of birth being blank
if (myDateOfBirth == "")
{
ifErrors = true;
ErrorMessage.push('Last name can not be blank');
}
//validate for date of birth not being formatted like (MM/DD/YYYY)
if (document.getElementById("txtDateOfBirth").value.length > 1)
{
if (! (txtDateOfBirth,valueOf().match(DateOfBirthValidate)));
{
ifErrors = true;
ErrorMessage.push('not a valid date of birth');
}
}
//create a variable to hold date, and see if it's greater than the current date
DateSupplied = new Date(DateSupplied);
if (DateSupplied > Dates)
{
ifErrors = true;
ErrorMessage.push('Date supplied can not be greater than the current date');
}
//va;idate for phone number
if (document.getElementById("txtPhoneNumber").value.length > 1)
{
if (! (txtPhoneNumber.valueOf().match(PhoneNumberValidate)))
{
ifErrors = true;
ErrorMessage.push('Phone number is not valid');
}
}
//successful validation
if (ifErrors == false)
{
ifErrors = true;
alert('Your registration has been processed');
//document.getElementById("RegisterForm").reset();
}
//Display list of messages in list
var DisplayMessage = "";
ErrorMessage.forEach(function (message)
{
DisplayMessage += "<li>" + message + "</li>";
}
);
document.getElementById("Errors").innerHTML = DisplayMessage;
}
<body>
<h3>Registration</h3>
<div>
<ul id="Errors"> </ul>
</div>
<br/>
<form ="RegisterForm">
<label id="lblUsername">Username:</label>
<input type="text" id="txtUsername" />
<br/>
<label id="lblPassword">Password:</label>
<input type="password" id="txtPassword" />
<br/>
<label id="lblFirstName">First Name:</label>
<input type="text" id="txtFirstName" />
<br/>
<label id="lblLastName">Last Name:</label>
<input type="text" id="txtLastName" />
<br/>
<label id="lblDateOfBirth">Date of Birth:</label>
<input type="text" id="txtDateOfBirth" />
<br/>
<label id="lblEmail">Email:</label>
<input type="text" id="txtEmail" />
<br/>
<label id="lblPhoneNumber">Email:</label>
<input type="text" id="txtPhoneNumber" />
<br/>
<input type="submit" value="Submit" onclick="Validation(); return false;" />
<input type="reset" value="reset Form" />
</form>
</body>

return false; does not stop the form from being submitted.
In order to achieve this behavior, you have to call .preventDefault() on the click event of the <input>, or on the submit event of the <form>. Example:
<form>
<input type="submit" onclick="someFn(event)">
</form>
<script>
function someFn(e) {
e.preventDefault();
console.log('form not submitted...');
}
</script>
To prevent all submit events in one go (regardless of which form element initiated it) you can call .preventDefault() on the form's onsubmit handler parameter (which is the submit event):
<form onsubmit="someFn(event)">
<input type="submit">
<button>Submit</button>
</form>
<script>
function someFn(e) {
e.preventDefault();
console.log('form not submitted...');
}
</script>
As a side-note, the submit input does not clear out your form. It sends it.
Because you haven't specified an action attribute on your <form> element, the submission is sent to the current URL.
Which, in practice, reloads the page.
Which, in practice renders a brand new instance of the form, obviously empty.
This is also the reason why "nothing happens at all". The default browser behavior when submitting a form is to actually load the <form>'s action URL (whether it's explicitly specified or not). You're navigating to that URL, along with the form's values. Which means you're not allowing the browser to finish running the code in Validation();. To wait around and see the results of Validation function, you have to prevent the default form submission behavior.
Docs:
<form>: MDN, HTML (Living Standard)
<input type="submit">: MDN, HTML (Living Standard)
Event.preventDefault(): MDN, DOM (Living Standard)

Enable Disabled Button if Input is not empty

I have one simple form which have two fields called first name with id fname and email field with email. I have submit button with id called submit-btn.
I have disabled submit button using javascript like this
document.getElementById("submit-btn").disabled = true;
Now I am looking for allow submit if both of my fields are filled.
My full javascript is like this
<script type="text/javascript">
document.getElementById("submit-btn").disabled = true;
document.getElementById("submit-btn").onclick = function(){
window.open("https://google.com",'_blank');
}
</script>
I am learning javascript and does not know how I can do it. Let me know if someone here can help me for same.
Thanks!

Id propose something like this
Use a block, which encapsulates the names of variables and functions inside the block scope
Make small functions, which do just one thing
Prefer addEventListener over onclick or onanything
There are two types of events you could use on the inputs: input and change. input will react on every keystroke, check will only react, if you blur the input element
I added a check for validity to the email field with checkValidity method
{
const btn = document.getElementById("submit-btn");
const fname = document.getElementById("fname");
const email = document.getElementById("email");
deactivate()
function activate() {
btn.disabled = false;
}
function deactivate() {
btn.disabled = true;
}
function check() {
if (fname.value != '' && email.value != '' && email.checkValidity()) {
activate()
} else {
deactivate()
}
}
btn.addEventListener('click', function(e) {
alert('submit')
})
fname.addEventListener('input', check)
email.addEventListener('input', check)
}
<form>
<input type="text" name="" id="fname">
<input type="email" name="" id="email">
<input type="submit" id="submit-btn" value="Submit">
</form>

This is the simplest solution I can imagine:
myForm.oninput = () => {
btn.disabled = fname.value == '' || email.value == '' || !email.checkValidity();
}
<form id="myForm">
<input type="text" name="" id="fname">
<input type="email" name="" id="email">
<input type="submit" id="btn" value="Submit" disabled>
</form>
Personally, I prefer to use regex to check the e-mail, instead of checkValidity(). Something like this:
/^[\w\-\.\+]+\#[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/.test(email.value);

Built a login form script but it's not working using JavaScript

I am trying to build a login.js script that listens for the login form submit event. When I try to run my code, it's not logging in or working properly
I' working with JavaScript, which is requested to use. I built the login form in HTML and have worked on the login function within JavaScript. It can;t be inline JavaScript, it has to be a separate script from HTML.
var count = 2;
function validate() {
var un = document.login.username.value;
var pw = document.login.password.value;
var valid = false;
var usernameArray = ["adrian#tissue.com",
"dduzen1#live.spcollege.edu",
"deannaduzen#gmail.com"
]
var passwordArray = ["welcome1", "w3lc0m3", "ch1c#g0"]
for (var i = 0; i < usernameArray.length; i++) {
if ((un == usernameArray[i]) && (pw == passwordArray[i])) {
valid = true;
break;
}
}
if (valid) {
alert("Login is successful");
window.location = "index.html";
return false;
}
var again = "tries";
if (count == 1) {
again = "try"
}
if (count >= 1) {
alert("Wrong username or password")
count--;
} else {
alert("Incorrect username or password, you are now blocked");
document.login.username.value = "You are now blocked";
document.login.password.value = "You are now blocked";
document.login.username.disabled = true;
document.login.password.disabled = true;
return false;
}
}
<!-- start of login form -->
<div class="login-page">
<div class="form">
<form class="register-form" onsubmit="return validate() ;" method="post">
<input type="text" placeholder="username" />
<input type="text" placeholder="password" />
<input type="text" placeholder="email id" />
<button>Create</button>
<p class="message">Already registered? Login
</p>
</form>
<form class="login-form">
<input type="text" placeholder="username" />
<input type="text" placeholder="password" />
<button>login</button>
<p class="message">Not registered? Register
</p>
</form>
</div>
</div>
It needs to allow the three login information I put into the code to log into the site. When logging in, it blinks as if it's doing something, but isn't going anywhere nor does it show that the person is logged in.

You are not validating correctly with the return sentence, also your onsubmit attribute was in the register form.
Use name attribute on forms
This will help you to identify your forms and inputs easily with JavaScript, otherwise you might have problems identifying which input is which in larger forms.
<form name="login" class="login-form">
<input name="user" type="text" placeholder="username" />
<input name="pass" type="text" placeholder="password" />
<button>login</button>
<p class="message">Not registered? Register
</p>
</form>
With this applied to your login form, you can reference it by doing document.login.
Take advantage over native HTML events in JavaScript
The way you are retrieving the username and password is a lot complex that it should, you can add an event listener in JavaScript and handle everything there:
const loginForm = document.login;
loginForm.addEventListener("submit", validate);
This will call validate every time the form is submitted. Also, it sends the event as a parameter, so you can receive it like this in your function:
function validate(event) {
event.preventDefault(); // Stop form redirection
let user = event.target.user.value,
pass = event.target.pass.value;
// REST OF THE CODE ...
}
This is easier since we added name attributes to the inputs, so we can identify them by user and pass.
Validation
NOTE: I do not recommend validating username:password data directly in the browser, since this is a big vulnerability and must be validated server-side.
You can simplify this validation by binding the username with its password in an object, instead of creating two arrays:
const accounts = {
"adrian#tissue.com": "welcome1",
"dduzen1#live.spcollege.edu": "w3lc0m3",
"deannaduzen#gmail.com": "ch1c#g0"
};
And then, having the inputs value saved in user and pass variables, you can do:
if (accounts[user] == pass) {
//SUCCESSFUL LOGIN
console.log('Correct. Logged in!');
} else {
//WRONG LOGIN CREDENTIALS
attempts--;
validateAttempts();
}
With the purpose of not having a lot of code in sight, you should create another function that its only job is to validate if you should block the user or not.
The result
I should mention that this will only work to validate the user form, if you need to save a session and keep an user logged in, you must use a server-side language.
I leave you a snippet with all of this changes working, see it for yourself:
const accounts = {
"adrian#tissue.com": "welcome1",
"dduzen1#live.spcollege.edu": "w3lc0m3",
"deannaduzen#gmail.com": "ch1c#g0"
};
const loginForm = document.login;
let attempts = 3;
loginForm.addEventListener("submit", validate);
function validate(event) {
event.preventDefault();
let user = event.target.user.value,
pass = event.target.pass.value;
if (accounts[user] == pass) {
//SUCCESSFUL LOGIN
console.log('Correct. Logged in!');
} else {
console.log('Wrong username or password.');
attempts--;
validateAttempts()
}
}
function validateAttempts() {
if (attempts <= 0) {
console.log("You are now blocked");
loginForm.user.value = "You are now blocked";
loginForm.pass.value = "You are now blocked";
loginForm.user.disabled = true;
loginForm.pass.disabled = true;
}
}
<form name="login" class="login-form">
<input name="user" type="text" placeholder="username" />
<input name="pass" type="text" placeholder="password" />
<button>login</button>
<p class="message">Not registered? Register
</p>
</form>

Can't submit form through javascript to php

I have a form in html which I want to run verification in Javascript first before POST ing to PHP. However the link up to the PHP section does not seem to be working despite the fact that I have assigned names to each input tag and specified an action attribute in the form tag.
Here is the HTML code for the form:
<form id="signupform" action="signupform.php" method="post">
<input type="text" name="Email" placeholder="Email Address" class="signupinput" id="email" />
<br />
<input type="password" name="Password" placeholder="Password" class="signupinput" id="passwordone" />
<br />
<input type="password" placeholder="Repeat Password" class="signupinput" id="passwordtwo" />
<br />
<input type="button" value="Sign Up" class="signupinput" onClick="verifypass()" id="submit" />
</form>
The button calls the javascript function which I use to verify the values of my form before sending to php:
function verifypass() {
var form = document.getElementById("signupform");
var email = document.getElementById("email").value;
var password1 = document.getElementById("passwordone").value;
var password2 = document.getElementById("passwordtwo").value;
var emailcode = /^(([^<>()\[\]\\.,;:\s#"]+(\.[^<>()\[\]\\.,;:\s#"]+)*)|(".+"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
if (emailcode.test(email)) {
if (password1.length > 6) {
if (password1 == password2) {
form.submit(); //this statement does not execute
} else {
$("#passwordone").notify("Passwords do not match!", {
position: "right"
})
}
} else {
$("#passwordone").notify("Password is too short!", {
position: "right"
})
}
} else {
$("#email").notify("The email address you have entered is invalid.", {
position: "right"
})
}
}

For some reason, some JavaScript implementations mix up HTML element IDs and code. If you use a different ID for your submit button it will work (id="somethingelse" instead of id="submit"):
<input type="button" value="Sign Up" class="signupinput" onClick="verifypass()" id="somethingelse" />
(I think id="submit" has the effect that the submit method is overwritten on the form node, using the button node. I never figured out why, perhaps to allow shortcuts like form.buttonid.value etc. I just avoid using possible method names as IDs.)

I'm not sure why that's not working, but you get around having to call form.submit(); if you use a <input type="submit"/> instead of <input type="button"/> and then use the onsubmit event instead of onclick. That way, IIRC, all you have to do is return true or false.

I think it would be better if you do it real time, for send error when the user leave each input. For example, there is an input, where you set the email address. When the onfocusout event occured in Javascript you can add an eventlistener which is call a checker function to the email input.
There is a quick example for handling form inputs. (Code below)
It is not protect you against the serious attacks, because in a perfect system you have to check on the both side.
Description for the Javascript example:
There is two input email, and password and there is a hidden button which is shown if everything is correct.
The email check and the password check functions are checking the input field values and if it isn't 3 mark length then show error for user.
The showIt funciton get a boolean if it is true it show the button to submit.
The last function is iterate through the fields object where we store the input fields status, and if there is a false it return false else its true. This is the boolean what the showIt function get.
Hope it is understandable.
<style>
#send {
display: none;
}
</style>
<form>
<input type="text" id="email"/>
<input type="password" id="password"/>
<button id="send" type="submit">Send</button>
</form>
<div id="error"></div>
<script>
var fields = {
email: false,
password: false
};
var email = document.getElementById("email");
email.addEventListener("focusout", emailCheck, false);
var password = document.getElementById("password");
password.addEventListener("focusout", passwordCheck, false);
function emailCheck(){
if(email.value.length < 3) {
document.getElementById("error").innerHTML = "Bad Email";
fields.email = false;
} else {
fields.email = true;
document.getElementById("error").innerHTML = "";
}
show = checkFields();
console.log("asdasd"+show);
showIt(show);
}
function passwordCheck(){
if(password.value.length < 3) {
document.getElementById("error").innerHTML = "Bad Password";
fields.password = false;
} else {
fields.password = true;
document.getElementById("error").innerHTML = "";
}
show = checkFields();
console.log(show);
showIt(show);
}
function showIt(show) {
if (show) {
document.getElementById("send").style.display = "block";
} else {
document.getElementById("send").style.display = "none";
}
}
function checkFields(){
isFalse = Object.keys(fields).map(function(objectKey, index) {
if (fields[objectKey] === false) {
return false;
}
});
console.log(isFalse);
if (isFalse.indexOf(false) >= 0) {
return false;
}
return true;
}
</script>