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Cannot read property 'input' of null at HTMLDocument.<anonymous> Javascript/HTML 2 part login error

I am trying to create a 2 part login, 1st part where you enter the username, click login, and the login takes you to a page where you enter your password. I have a js function where I check if the username field is null, because I want to require the user to enter something in the text field before clicking the button redirects them to the second part of the login. However, I am getting an error: Uncaught ReferenceError: loginCheck is not defined at HTMLInputElement.onclick
here is my code
var formhtml = '<div class="container"><label for="userNameBox"><b>Username </b></label><input type="text" id="userNameBox" placeholder="Enter Username" required ="required"><br></br> <input type="button" id ="loginButton" value="Login"onclick="javascript:loginCheck()"/></div>'
function loginCheck(){
var x = null;
if(document.getElementById("userNameBox").value !=null){
document.getElementById("loginButton").onclick = function () {
location.href = "myLogin.Part2";
}
}
else{
alert("username required");
location.reload();
}
}
$('.login').click(function(e)
{
e.preventDefault();
if ($('#loginbox').html() == '')
$('#loginbox').html(formhtml);
$('#loginbox').show();
return false;
});

You seem to be mixing a lot of Vanilla JavaScript and jQuery. Although that's not wrong, it might help you with development by choosing one or the other.
Like #Teemu said, the value of an input is never null. If it is empty than the value will be represented as an empty string "".
The loginCheck function will add an event listener to the loginButton element. But that element already has an onclick attribute which calls the loginCheck function. This will not run as you would like it to. Instead of both add an event listener with either addEventListener (Vanilla JavaScript) or with the on method (jQuery)
I've tried to convert your code so that it uses jQuery. Check it out and let me know if your problem has been resolved.
const $document = $(document);
const $login = $("#login");
const $loginBox = $("#loginbox");
const $formElement = $(`
<div class="container">
<label for="userNameBox"><b>Username </b></label>
<input type="text" id="userNameBox" placeholder="Enter Username" required="required"><br>
<input type="button" id="loginButton" value="Login"/>
</div>
`);
$document.on("click", "#loginButton", function() {
const $userNameBox = $("#userNameBox");
if ($userNameBox.val() !== "") {
location.href = "myLogin.Part2";
} else {
alert("username required");
location.reload();
}
});
$login.on("click", function (event) {
if ($loginBox.children().length === 0) {
$loginBox.append($formElement);
}
$("#loginbox").show();
event.preventDefault();
return false;
});

Onclick and jQuery click working together but return false not working in jquery

Onclick and jQuery click working together but return false not working in jquery. I want to validate fields before on onclick open next page. Problem with my code is that if filed are blank in that case it open next page. I use return false in each empty case. So until all fields are not filled up. next page should not open.
Html Code
<button id="onepage-guest-register-button" type="button" class="button secondary" onclick="$('login:guest').checked=true; checkout.setMethod();"><span><span><?php //echo $this->__('Checkout as Guest') ?></span></span></button>
jQuery Code
jQuery('#onepage-guest-register-button').click(function(e){
var email=jQuery('#login-email').val();
jQuery('.validate-email').attr('value', email);
var login_name = jQuery('#login_name').val();
var login_phone = jQuery('#login_phone').val();
var login_email = jQuery('#login_email').val();
alert("name"+login_name+'phone'+login_phone+'email'+login_email);
if(login_name==''){ jQuery('.login_name').text('Please enter full name'); return false; }else{ jQuery('.login_name').empty();}
if(login_phone==''){ jQuery('.login_phone').text('Please enter Phone Number');return false;}else{ jQuery('.login_phone').empty();}
if(login_email==''){ jQuery('.login_email').text('Please enter Phone email');return false;}else{ jQuery('.login_email').empty();}
//alert('trigger');
jQuery('#onepage-guest-register-button').trigger('onclick');
});

Don't mix onclick attribute with onclick event handler. It's just plain silly.
In most cases, it's better to go with the latter.
1) Remove onclick attribute
<button id="onepage-guest-register-button" type="button" class="button secondary"><span><span><?php echo $this->__('Continue') ?></span></span></button>
2) Move the logic into your onclick event handler.
jQuery('#onepage-guest-register-button').click(function(e){
// no idea
var email = jQuery('#login-email').val();
jQuery('.validate-email').attr('value', email);
// get values
var login_name = jQuery('#login_name').val();
var login_phone = jQuery('#login_phone').val();
var login_email = jQuery('#login_email').val();
// flag if errors is found; assume no errors by default
var err = false;
// clear errors?
jQuery('.login_name').empty();
jQuery('.login_phone').empty();
jQuery('.login_email').empty();
// show errors if any
if (login_name == '') {
jQuery('.login_name').text('Please enter full name');
err = true;
}
if (login_phone == ''){
jQuery('.login_phone').text('Please enter Phone Number');
err = true;
}
if (login_email == ''){
jQuery('.login_email').text('Please enter Phone email');
err = true;
}
// do the appropriate action depending if there are errors or not
if (err) {
return false;
} else {
$('login:guest').prop('checked', true);
checkout.setMethod();
}
});

Javascript form validation code looping

The following code loops when the page loads and I can't figure out why it is doing so. Is the issue with the onfocus?
alert("JS is working");
function validateFirstName() {
alert("validateFirstName was called");
var x = document.forms["info"]["fname"].value;
if (x == "") {
alert("First name must be filled out");
//return false;
}
}
function validateLastName()
{
alert("validateLastName was called");
var y = document.forms["info"]["lname"].value;
if (y == "") {
alert("Last name must be filled out");
//return false;
}
}
var fn = document.getElementById("fn");
var ln = document.getElementById("ln");
fn.onfocus = validateFirstName();
alert("in between");
ln.onfocus = validateLastName();

There were several issues with the approach you were taking to accomplish this, but the "looping" behavior you were experiencing is because you are using a combination of alert and onFocus. When you are focused on an input field and an alert is triggered, when you dismiss the alert, the browser will (by default) re-focus the element that previously had focus. So in your case, you would focus, get an alert, it would re-focus automatically, so it would re-trigger the alert, etc. Over and over.
A better way to do this is using the input event. That way, the user will not get prompted with an error message before they even have a chance to fill out the field. They will only be prompted if they clear out a value in a field, or if you call the validateRequiredField function sometime later in the code (on the form submission, for example).
I also changed around your validation function so you don't have to create a validation function for every single input on your form that does the exact same thing except spit out a slightly different message. You should also abstract the functionality that defines what to do on each error outside of the validation function - this is for testability and reusability purposes.
Let me know if you have any questions.
function validateRequiredField(fieldLabel, value) {
var errors = "";
if (value === "") {
//alert(fieldLabel + " must be filled out");
errors += fieldLabel + " must be filled out\n";
}
return errors;
}
var fn = document.getElementById("fn");
var ln = document.getElementById("ln");
fn.addEventListener("input", function (event) {
var val = event.target.value;
var errors = validateRequiredField("First Name", val);
if (errors !== "") {
alert(errors);
}
else {
// proceed
}
});
ln.addEventListener("input", function (event) {
var val = event.target.value;
var errors = validateRequiredField("Last Name", val);
if (errors !== "") {
alert(errors);
}
else {
// proceed
}
});
<form name="myForm">
<label>First Name: <input id="fn" /></label><br/><br/>
<label>Last Name: <input id="ln"/></label>
</form>

Not tested but you can try this
fn.addEventListener('focus', validateFirstName);
ln.addEventListener('focus', validateLastName);

How to validate login trough post request upon clicking the login button in javascript?

I'm having problems getting this code to validate when clicking on the login button.
** my html code **
<form action="abc.php"
method="post"
onsubmit="return jcheck();">
<div id="id_box">
<input type="text"
name="email"
id="id_text" placeholder="E-mail" >
<div id="pass_box">
<input type="password"
name="password" id="pass_text" placeholder="Password">
<div id="submit_box">
<input
type="submit"
id="sub_box"
onClick="click_event()"
value="Login">
my javascript code:
function click_event(){
jcheck();
function validate_ID(){
var email = document.getElementById('id_text');
var filter = /^[a-z0-9](\.?[a-z0-9]){1,}#threadsol\.com$/;
var filter1 = /^[a-z0-9](\.?[a-z0-9]){1,}#intellocut\.com$/;
var flag=0;
if (filter.test(email.value)==false
&& filter1.test(email.value)==false ) {
$('#warn_pass').html("Enter Valid Email or Password");
$("#e_asterics").html("");
return false;
} else
return true;
}
function validate_Pass() {
var pass =document.getElementById('pass_text');
var filter = /^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[^a-zA-Z0-9])(?!.*\s). 4,}$/;
if (filter.test(pass.value)==false ) {
$('#warn_pass').html("Enter Valid Email or Password");
$("#p_asterics").html("");
return false;
} else
return true;
}
function jcheck();
$("#e_asterics").html("");$("#p_asterics").html("");
$('#warn_text').html("");$('#warn_pass').html("");
var name = jQuery.trim($("#id_text").val());var pas = jQuery.trim($("#pass_text").val());
if ((name.length == 0) && (pas.length == 0)) {
$('#warn_text').html("*Indicates required field");
$('#warn_pass').html("* Indicates required field");
$("#e_asterics").html("*");$("#p_asterics").html("*"); }
else if (name.length == 0)) {
$("#e_asterics").html("*");
$("#p_asterics").html("");
$('#warn_pass').html("Email Id Required");
} else if ((pas.length == 0)) {
if(name.length != 0)
{
validate_ID();
} else {
$("#e_asterics").html("*");
$('#warn_text').html("Enter Email Id");
}
$("#p_asterics").html("*");
$('#warn_pass').html("Password Required");
}
}
return false;
}

For starters you should always indent your code so errors are easier to find. I helped you do a bit of indenting and there are a lot of problems in the code. One thing you are doing wrong is you need to close functions, else branches and html tags.
All HTML tags should end with an end tag or be closed immediately.
Example <div></div> or <div /> if you don't do this the browser may render your page differently on different browsers. You have missed this on your input tags you divs and your form tag. Perhaps you should check the whole html document for more of these errors.
Functions should in javascript should always look like this
function name(parameters, ...) {
}
or like this
var name = function(parameters, ...) {
}
the the name and parameters may vary but generally the function should look like this.
if statements else branches and else if branches should all have enclosing brackets for their code.
if () {
//code
} else if () {
//code
} else {
//code
}
If you do not close start and close else brackets the javascript will behave in very strange and unexpected ways. In fact i think your code might not even compile.
If you are using chrome please press Ctrl + Shift + J and look in the Console tab. You should see some error messages there. When you click the submit button.
Also using onClick on the submit button may be dangerous as I don't think this blocks submit. A better way to achieve the requested functionality is probably to either use a button type input and go with onClick or use the onSubmit function on the form. You are currently using both and its really no way to tell if click_event or jcheck will run first. Perhaps you should debug and see in which order the function calls happen. You can use chrome to debug by pressing CTRL + Shift + J and setting debug points in the Source tab.
You have a minor stylistic error as well where you compare the result of the regexp test() with false. The return value of test is already a Boolean and does not need to be compared.
Here is a guestimation of how the HTML should look. Its hard to say if its right as I have no more info to go on than your code and it has a lot of problems.
<form action="abc.php" method="post" onsubmit="return jcheck();">
<div id="id_box">
<input type="text" name="email" id="id_text" placeholder="E-mail" />
</div>
<div id="pass_box">
<input type="password" name="password" id="pass_text" placeholder="Password">
</div>
<div id="submit_box">
<input
type="submit"
id="sub_box"
value="Login" />
</div>
</form>
Here is what the js might look like. Here the missing brackets makes it difficult to tell where functions should end so I have had to guess a lot.
/* I find it hard to belive you wanted to encapsule your functions inside the
click_event function so I took the liberty of placing all
functions in the glonbal scope as this is probably what you inteneded.
I removed the click_event handler as it only does the same thing as the onSubmit.
*/
function validate_ID() {
var email = document.getElementById('id_text');
var filter = /^[a-z0-9](\.?[a-z0-9]){1,}#threadsol\.com$/;
var filter1 = /^[a-z0-9](\.?[a-z0-9]){1,}#intellocut\.com$/;
var flag=0;
// Or feels better here as there is no way the email ends with bot #intellocut and #threadsol
// It also feels strange that these are the invalid adresses maby you messed up here and should change
// the contents of the else and the if branch.
if (filter.test(email.value) || filter1.test(email.value)) {
$('#warn_pass').html("Enter Valid Email or Password");
$("#e_asterics").html("");
return false;
} else {
return true;
}
}
// This funcion is not used Im guessing you should have used it in
function validate_Pass() {
var pass =document.getElementById('pass_text');
/* The filter below could cause problems for users in deciding password unless
you tell them some where what the rules are.
It was missing a { bracket before the 4 at the end that I added make sure
it is right now. If you are going to use the code.
*/
var filter = /^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[^a-zA-Z0-9])(?!.*\s). {4,}$/;
if (filter.test(pass.value)) {
$('#warn_pass').html("Enter Valid Email or Password");
$("#p_asterics").html("");
return false;
} else {
return true;
}
}
/* There are betterways to deal with multiple validation than chaining them like
this but Im guessing this will work. Im guessing that if you want to use the
password validation you should call it some where in this function.
like so 'validate_Pass()'
*/
function jcheck() {
$("#e_asterics").html("");$("#p_asterics").html("");
$('#warn_text').html("");$('#warn_pass').html("");
var name = jQuery.trim($("#id_text").val());var pas = jQuery.trim($("#pass_text").val());
if ((name.length === 0) && (pas.length === 0)) {
$('#warn_text').html("*Indicates required field");
$('#warn_pass').html("* Indicates required field");
$("#e_asterics").html("*");
$("#p_asterics").html("*"); }
else if (name.length === 0) {
$("#e_asterics").html("*");
$("#p_asterics").html("");
$('#warn_pass').html("Email Id Required");
} else if (pas.length === 0) {
if(name.length !== 0) {
validate_ID();
} else {
$("#e_asterics").html("*");
$('#warn_text').html("Enter Email Id");
}
}
}

How to check for empty values on two fields then prompt user of error using javascript

I hope I can explain this right I have two input fields that require a price to be entered into them in order for donation to go through and submit.
The problem that I am having is that I would like the validation process check to see if one of the two fields has a value if so then proceed to submit. If both fields are empty then alert.
This is what I have in place now after adding some of the input i received earlier today:
function validate_required(field,alerttxt)
{
with (field)
{
if (value==null||value=="")
{
alert(alerttxt); return false;
}
else
{
return true;
}
}
}
function validate_form(thisform)
{
with (thisform)
{
if (validate_required(billing_name_first,"You must enter your first name to donate")==false)
{billing_name_first.focus();return false;}
else if (validate_required(billing_name_last,"You must enter your last name to donate")==false)
{billing_name_last.focus();return false;}
else if (validate_required(billing_address_street1,"You must enter your billing street address to donate")==false)
{billing_address_street1.focus();return false;}
else if (validate_required(billing_address_city,"You must enter your billing address city to donate")==false)
{billing_address_city.focus();return false;}
else if (validate_required(billing_address_state,"You must enter your billing address state to donate")==false)
{billing_address_state.focus();return false;}
else if (validate_required(billing_address_zip,"You must enter your billing address zip code to donate")==false)
{billing_address_zip.focus();return false;}
else if (validate_required(billing_address_country,"You must enter your billing address country to donate")==false)
{billing_address_country.focus();return false;}
else if (validate_required(donor_email,"You must enter your email address to donate")==false)
{donor_email.focus();return false;}
else if (validate_required(card_number,"You must enter your credit card number to donate")==false)
{card_number.focus();return false;}
else if (validate_required(card_cvv,"You must enter your credit card security code to donate")==false)
{card_cvv.focus();return false;}
else if (validate_required(input1,"Need to enter a donation amount to continue")==false && validate_required(input2, "Need to enter a donation amount to continue")==false)
{
input1.focus();
return false;
}
}
}
This works fine... other than the fact that I get a message that reads error undefined... which i click ok about 2 times then I get the correct alert and instead of allowing me to correct the problem in IE7 and IE8 the form just processes.
Thanks guys any help would do
Matt

If I am understanding correctly, you only want to do the alert if both of the inputs are empty. If that's the case here's a refactoring of your code that will handle that.
function validate_required(field)
{
with (field)
{
if (value==null||value=="")
{
return false;
}
else
{
return true;
}
}
}
function validate_form(thisform)
{
with (thisform)
{
if (validate_required(input1)==false && validate_required(input2)==false)
{
alert('Need a donation to continue');
input1.focus();
return false;
}
}
}

take the alert() out of your assessment function- you're trying to do too much at once. a function to determine if input is valid or not should do only that one thing.
determine the state of your inputs first and then do something like
var field1Pass = validate_required(input1);
var field2Pass = validate_required(input2);
if ( !(field1Pass && field2Pass) ) {
alert("Need a donation amount to continue");
// TODO: logic to determine which field to focus on
return false;
}

var msg = "Need a donation amount to continue";
function validate_required(value) {
if(isNaN(value) || value == null || value == "") {
return false;
}
return true;
}
function validate_form(thisform) {
var i1 = validate_required($(thisform.input1).val());
var i2 = validate_required($(thisform.input2).val());
if(!(i1 && i2)) {
alert(msg);
thisform.input2.focus();
return false;
}
}

Look at the jQuery validation plugin. With the plugin it would just be a matter setting up the rules properly. You could get fancier and replace the default messages if you want. Check out the examples.
<script type="text/javascript">
$(function() {
$('form').validate({
'input1': {
required: {
depends: function() { $('#input2').val() == '' }
}
}
});
});
</script>
This sets it up so that input1 is required if input2 is empty, which should be sufficient since if input1 has a value, you don't need input2 and if neither has a value, then it will show your message for input1.
<input type="text" name="input1" />
<input type="text" name="input2" />

Here's my take, with refocusing on the first field that failed:
<body>
<form action="#" onsubmit="return validate(this);">
<input type="text" name="val0" /><br />
<input type="text" name="val1" /><br />
<input type="submit" />
</form>
<script type="text/javascript">
function validate(form) {
var val0Elem = form.val0, val1Elem=form.val1, elementToFocus;
// check fields and save where it went wrong
if (!numeric(val0Elem.value)) {elementToFocus=val0Elem;}
else if (!numeric(val1Elem.value)) {elementToFocus=val1Elem;}
// if there is an element to focus now, some validation failed
if (elementToFocus) {
alert('Enter numbers in both fields, please.')
// using select() instead of focus to help user
// get rid of his crap entry :)
elementToFocus.select();
// ..and fail!
return false;
}
// Helper function, "if a string is numeric":
// 1: it is not 'falsy' (null, undefined or empty)
// 2: it is longer than 0 too (so that '0' can be accepted)
// 3: it passes check for numericality using the builtin function isNaN
function numeric(s) {return (s && s.length>0 && !isNaN(s));}
}
</script>
</body>