Develop Reference

Make an action after two events happened - JS

Want to change submit button color after email verification and checkbox marked. Added listeners on changes and they work well. But have no idea how to find out when this events are going to happen to launch function what is going to change submit button color.
```
https://jsfiddle.net/nvologdins/brfj2xk1/
```

Here is a basic example of how to do this.
I also changed the logic a bit to update the values if the user changes them again. - #Ultimater mentioned this also.
function setupButton() {
if (validEmail && validCheckbox) {
// add/show/enable submit button or simply change the color
button.style.color = "red";
} else {
// remove/hide/disable submit button revert the changes
button.style.color = "";
}
}
form.input.addEventListener('input', (event)=>{
validEmail = emailRegex.test(event.target.value);
setupButton();
})
form.checkbox.addEventListener('change', (event)=>{
validCheckbox = event.target.checked;
setupButton();
})
I would also suggest a different method to validate the form using the Constraint Validation API.
Every element has a validity check which can easily be accessed on the form element using formElement.checkValidity() and returns true/false if all (required) fields inside the form are filled with valid values.
<form oninput="this.querySelector('#submitButton').disabled = !this.checkValidity();" onsubmit="event.preventDefault(); console.log('Submit prevented but the form seems to be valid.'); return false;">
<fieldset>
<label for="newslettermail">E-Mail</label>
<!-- you could also define a more specific pattern on the email input since email would allow foo#bar as valid mail -->
<input type="email" id="newslettermail" required>
</fieldset>
<fieldset>
<input type="checkbox" id="newsletterAcceptTos" required>
<label for="newsletterAcceptTos">I accept the Terms of Service</label>
</fieldset>
<fieldset>
<label for="textFieldWithPattern">Enter <strong>foo</strong> or <strong>bar</strong></label>
<input type="text" id="textFieldWithPattern" pattern="^(foo|bar)$" required>
</fieldset>
<button type="submit" id="submitButton" disabled>Submit</button>
<button type="submit">Force submit (will show errors on invalid input)</button>
</form>
Using this, the browser for itself checks the values if they contain a valid value.
An input[type=email] with required flag must contain a valid mail address.
A checkbox with required flag, must be checked.
An input with required and a pattern must contain a value matching the regular expression from the pattern-attribute.

No need to create extra variables and listen on two form elements separately... You can check the whole thing and update accordingly only by listening to the form element
let form = document.querySelector('form');
let input = document.getElementById('input');
let checkbox = document.getElementById('checkbox');
let submit = document.getElementById('button');
const emailRegex = /^(([^<>()\[\]\\.,;:\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,}))$/
form.addEventListener('change', (event) => {
if (checkbox.checked && emailRegex.test(input.value)) {
submit.style.color = "red";
} else {
submit.style.color = "black"
}
})
//Update
input.addEventListener('input', () => {
const changeEvent = new Event('change');
form.dispatchEvent(changeEvent)
})
<form class="main__emailAndTerms emailAndTerms">
<div class="emailAndTerms__email">
<input type="text" id="input" placeholder="Type your email address here...">
<label class="emailAndTerms__terms">I agree to <span class="terms__link">terms of service</span>
<input type="checkbox" class="terms__checkbox" id="checkbox">
<span class="terms__checkbox_custom"></span>
</label>
<button type="submit" class="email__submitButton" id="button">Submit</button>
</div>
</form>

JavaScript function not working on form submission

I've got an HTML form, and when it is submitted, I want a JavaScript function I have defined to run. However, no matter what, the function I've written is not recognised. Here is the HTML form:
<form id="compose-form">
<div class="form-group">
From: <input disabled class="form-control" value="{{ request.user.email }}">
</div>
<div class="form-group">
To: <input id="compose-recipients" class="form-control">
</div>
<div class="form-group">
<input class="form-control" id="compose-subject" placeholder="Subject">
</div>
<textarea class="form-control" id="compose-body" placeholder="Body"></textarea>
<input type="submit" class="btn btn-primary"/>
</form>
And then here is my JavaScript code:
document.addEventListener('DOMContentLoaded', function() {
// #compose is the id of the div the form #compose-form is in
document.querySelector('#compose').addEventListener('click', compose_email);
document.querySelector('#compose-form').addEventListener('submit', () => send_email(event));
});
function send_email(event) {
event.preventDefault();
// Note this isn't the actual content of my function, but even this simple code doesn't work
alert('Hello');
return false;
}
function compose_email() {
document.querySelector('#emails-view').style.display = 'none';
document.querySelector('#compose-view').style.display = 'block';
// Note: this function does work completely.
document.querySelector('#compose-recipients').value = '';
document.querySelector('#compose-subject').value = '';
document.querySelector('#compose-body').value = '';
}
WHAT I'VE TRIED:
I've moved the functions above the event listener in my JavaScript
I've alternately removed both the event.preventDefault(); and the return false;, removed both, kept both.
I've tried defining the function separately, as I have it here, and doing the code as an anonymous function
I've tried both document.querySelector('#compose-form').addEventListener('submit', etc.) and document.querySelector('#compose.form').onsubmit = send_email(event).
I know the form doesn't have an action=; it isn't relevant. In all the searching I have done, this code should prevent the form from submitting, and perform the function, but for whatever reason it doesn't. When I click the submit button only a ? is added to the URL, which I recognise as wanting queries, and that's handled elsewhere with my actual send_email function. I just want to know why my function appears to not be recognised and/or run.

It looks it has issue with document.querySelector('#compose').addEventListener('click', compose_email); Where is the element with id compose? It's not finding it.
I commented out that and it's firing the alert. Please check below
document.addEventListener('DOMContentLoaded', function() {
// #compose is the id of the div the form #compose-form is in
//document.querySelector('#compose').addEventListener('click', compose_email);
document.querySelector('#compose-form').addEventListener('submit', () => send_email(event));
});
function send_email(event) {
event.preventDefault();
// Note this isn't the actual content of my function, but even this simple code doesn't work
alert('Hello');
return false;
}
function compose_email() {
document.querySelector('#emails-view').style.display = 'none';
document.querySelector('#compose-view').style.display = 'block';
// Note: this function does work completely.
document.querySelector('#compose-recipients').value = '';
document.querySelector('#compose-subject').value = '';
document.querySelector('#compose-body').value = '';
}
<form id="compose-form">
<div class="form-group">
From: <input disabled class="form-control" value="{{ request.user.email }}">
</div>
<div class="form-group">
To: <input id="compose-recipients" class="form-control">
</div>
<div class="form-group">
<input class="form-control" id="compose-subject" placeholder="Subject">
</div>
<textarea class="form-control" id="compose-body" placeholder="Body"></textarea>
<input type="submit" class="btn btn-primary"/>
</form>

Check Field Validity and Fields Filled Before Submission?

I am revising this question as I have changed things.
I have a form with a few fields, three of which have regex validation. I also have a function which checks if all fields are filled before the submit button is enabled, this works fine. However if the fields are filled but the invalid fields ae invalid, I can still submit the form. I want to know if I am able to merge my functions so that I can check if the fields are filled AND valid before enabling the submit button?
I have tried adding an extra && clause but this doesn't work, and I tried to implement the jQuery validate plug-in but it seemed very limited and I can't validate a postcode using it.
Here is a reduced version of my project:
// ~~~ postcode validation
function validatePostcode(postcode) {
var pcode = /^[a-zA-Z]{1,2}[0-9][0-9A-Za-z]{0,1} {0,1}[0-9][A-Za-z]{2}$/;
return pcode.test(postcode);
}
function validateP() {
var postcode = $("#postcode").val();
if (validatePostcode(postcode)) {
$("#postcode").removeClass("is-invalid");
return true;
} else {
alert('Please enter a valid postcode');
$("#postcode").addClass("is-invalid");
}
return false;
}
// ~~~ validate if form is filled completely, toggles submit & edit button
$(document).on('change keyup invalid', '.required', function(e) {
var disabled = true;
$(".required").each(function() {
var value = this.value;
if ((value) && (value.trim() != '')) {
disabled = false;
$('.toggle-disabled').prop("disabled", false);
} else {
disabled = true;
$('.toggle-disabled').prop("disabled", true);
return false;
}
});
});
<link href="https://cdn.jsdelivr.net/npm/bootstrap#5.0.0-beta1/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-giJF6kkoqNQ00vy+HMDP7azOuL0xtbfIcaT9wjKHr8RbDVddVHyTfAAsrekwKmP1" crossorigin="anonymous">
<div class="col-md-6">
<input type="text" id="postcode" class="input postcode form-control required" onchange="validateP()" placeholder="Post Code" name="postcode" required>
</div>
<div class="col-md-6">
<input id="submit" class="btn btn-danger toggle-disabled" type="submit" value="Submit" disabled>
</div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

Use below regex:
/^([0-9a-zA-Z\-\._]+)#([0-9a-zA-Z\-\._]+)\.([a-zA-Z]){2,7}$/

Why The Validation is not working for the provided html/ js code

I want the to get the required in the html page if none is selected.
function validation() {
var country = getElementById("country");
if (country.value = "") {
documnet.getElementById("countryy").innerHTML = "Required";
return false;
} else
return true;
}
<form onsubmit="return validation();">
<select id="country"><span id="countryy"></span>
</select><br>
<input type="submit" name="Submit" value="Submit">
</form>
Why The Validation is not working for the provided html/ js code. I want the to get the required in the html page if none is selected. I am new to js learning.

Several issues
Spelling mistake in the document.getElementById
missing document on the other document.getElementById
No preventDefault which will submit the form if any JS errors
= is assignment - you need == or === to compare
span needs to be outside the select
You did not use value="Default" in the "NONE" options
It is not recommended to have inline event handlers. Here is a better version
Note I added a class to toggle the required in case the user changes the select to conform
window.addEventListener("load", function() {
const errorSpan = document.getElementById("countryy"); // cache the elements
const country = document.getElementById("country");
document.getElementById("myForm").addEventListener("submit", function(e) {
const val = country.value; // get the value
if (val === "") {
e.preventDefault(); // stop submit
}
errorSpan.classList.toggle("hide",val); // hide if value
})
country.addEventListener("change",function() { // if user changes the select
errorSpan.classList.toggle("hide",this.val); // hide if value
})
})
.hide { display : none; }
<form id="myForm">
<select id="country">
<option value="">NONE</option>
<option value="ABDUL">ABDUL</option>
<option value="SULE">SULE</option>
</select> <span id="countryy" class="hide">Required</span><br>
<input type="submit" name="Submit" value="Submit">
</form>
HOWEVER you could remove all the script and just add required attribute to the select and keep the empty default
<form id="myForm">
<select id="country" required>
<option value="">NONE</option>
<option value="ABDUL">ABDUL</option>
<option value="SULE">SULE</option>
</select><span id="countryy"></span><br>
<input type="submit" name="Submit" value="Submit">
</form>

Use required attribute in the select tag. It will considered in html 5 validation.
https://www.w3schools.com/tags/tryit.asp?filename=tryhtml5_select_required

Can't submit form with data-live-search as true (Bootstrap-select)

I'm making a issue reporting form with categories and sub categories. The form also requires the user to add their e-mail address (from a list). The list has the data-live-search = true to give them the possibility to search for it in the list.
The form submits if you first start to type in the search field for the e-mail and then selects it, but if you don't write in the search bar and just select it from the list (without typing anything), the form won't submit... This is what the form looks like (a simplified version, but still not working):
<form role="form" name="form" id="form" action="file.php" method="post">
<!-- AUTHOR NAME -->
<div class="form-group" id="form-group-author-name">
<label class="sr-only" for="author-name">Author's name</label>
<input type="text" name="author-name" id="form-author-name" placeholder="Author's name" class="form-control" required>
</div>
<!-- AUTHOR E-MAIL -->
<div class="form-group" id="form-group-author-email">
<select class="selectpicker" name="author-email" id="form-author-email" data-width="100%" title="Author's e-mail" data-live-search="true" required>
<option>email1#example.com</option>
<option>email2#example.com</option>
<option>email3#example.com</option>
<option>email4#example.com</option>
<option>email5#example.com</option>
</select>
<p class="help-block">Search for your e-mail.</p>
</div>
<button type="submit" class="btn">Submit</button>
</form>
I've also tried to add an event listener to the select field and use $("#" + "form-author-email").selectpicker('refresh'); and document.getElementById("form-author-email").value = $("#" + "form-author-email").val(); in case it was because of the field not updateing, but that wasn't working either.
If I use console.log($("#" + "form-author-email").val()); I still get the value selected, so I don't understand what the problem is.

I've figured out the problem. I've added a jQuery validation function (for all input fields) that used e.preventDefault(); and added a error styling-class if the input was empty, which it would always be if they didn't type anything into the search bar. I've add the code below in case anybody has done the same thing:
jQuery(document).ready(function() {
$('.form input[type="text"]').on('focus', function() {
$(this).removeClass('error');
});
$('.form').on('submit', function(e) {
$(this).find('input[type="text"]').each(function(){
if( $(this).val() == "" ) {
e.preventDefault();
$(this).addClass('error');
}
else {
$(this).removeClass('error');
}
});
});
});