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Field validation for not null or empty is not triggering

I'm trying to send messaging to the user that a field is required if they fail to input a value. I want the error to be displayed on the field itself, rather than a global error message at the top of the page.
If I do not enter any data into the form, it still allows submission. However, if I do not enter a username but I do enter mismatched passwords, the username field receives the validation message "Passwords do not match".
So, it appears to me, that for some reason my code to check if the input is null is not passing as True and so the function continues to my next condition.
Why isn't this function catching nulls?
<form action="/register" method="post">
<div class="form-group">
<input autocomplete="off" autofocus class="form-control" name="username" placeholder="Username" type="text"
oninput="checkNull(this)" id="username">
</div>
<div class="form-group">
<input class="form-control" name="password" placeholder="Password" type="password" oninput="checkNull(this)"
id="password">
</div>
<div class="form-group">
<input class="form-control" name="confirmPassword" placeholder="Confirm Password" type="password"
oninput="check(this)" id="confirmPassword">
</div>
<script language='javascript' type='text/javascript'>
function check(input) {
if (input.value != document.getElementById('password').value) {
input.setCustomValidity('Passwords do not match');
} else {
input.setCustomValidity('');
}
}
if (input.value == "" || input.value == null) {
input.setCustomValidity('This field is required');
}
else {
input.setCustomValidity('');
}
</script>
<button class="btn btn-primary" type="submit">Register</button>
</form>
I've tried some additional troubleshooting. I split my functions out, one to check for matching passwords, one to check for no input. I realized that by calling them in the same function I was comparing each to the password which is a problem.
As a sanity check, I then set to check for a specific string "foo". When passing in "foo", the error displays as expected, so I know at least the function is getting called.
I then tried to use "===" to compare the value rather than "==", but that didn't work either.
Code updated to reflect most recent changes.

When submit your form, it is not calling check() function. So, if you not touch any input, they will not be validated.
You can solve this by adding onsubmit="return validate()" to <form /> tag:
<form action="/register" method="post" onsubmit="return validate()">
Your validation function could be simple as:
var isValid = true;
function validate() {
isValid = true;
document.querySelectorAll('.form-control').forEach(check);
return isValid;
}
Notice the return keyword. When return value is false the submitting action will be cancelled. check() function should also mutate isValid variable:
function check(input) {
if (input.value == "" || input.value == null) {
input.setCustomValidity('This field is required');
isValid = false;
}
else if (input.type == 'password' && input.value != document.getElementById('password').value) {
input.setCustomValidity('Passwords do not match');
isValid = false;
}
else {
input.setCustomValidity('');
}
}
Also, you should only check if passwords are the same if you are validating a password input.
You can accomplish this by adding the extra condition to password validation: input.type == 'password'

You are calling your check method onchange, if you do not enter any text in the username field, your check method will not be called. So, the simple way to do this is to add required attribute on all your fields.
If you want to do it using JS, look at onsubmit method that gets triggered when the form's submit button is clicked.
Also, you should have three different methods for validating each of your fields. It will be hard to maintain and you will be cramping up one method with various checks.

You are using deprecated techniques here.. You should never attach a function to a form element in-line (within the html tag).
When it comes to checking password on keyup, you could use something like this with jquery:
var pwInputs = $(this).find('input[type=password]');
$('input[type=password]').keyup(() => {
pwarr = new Array();
pwInputs.each(function() {
pwarr.push($(this));
});
if (pwarr[0].val() != pwarr[1].val()) {
// Do work
}
if (pwarr[0].val() == null || pwarr[0].val() == "" & pwarr[1].val() == null || pwarr[1].val() == "") {
// Do Work
}
});
You could use jquery in a similar fashion to check values on submit.
$('#formid').on('submit', function() { // Do work })

How to handle alphanumeric and null in JavaScript?

We are facing an issue on handling null, because if the value is null, it is not reaching the server. Below is the code snippet:
<input ... onchange="return checkEmpty(this);" />
And the JavaScript:
function checkEmpty(value) {
alert("Empty Check() "+value);
if (myTrim(value.length == 0)) {
alert("please Enter Value!"+ value +" value");
return false;
}
return true;
}
We are trying to display one popup for null value and the request should go to the server, but some exception is occurring we are unable to identify it and the request is not coming to server.

You can do this:
if (variable == null) {
// do something
}
--which is 100% equivalent to the more explicit but less concise:
if (variable === undefined || variable === null) {
// do something
}

While there are ways to solve this specific problem (and the other answer(s) manage to answer that), I'll try to address a more general one.
What you essentially want is the form control to not be empty. Well, you don't need JavaScript for that at all
<input ..... required>
That will prevent the form from submitting unless the required field was filled.
<form>
Try to submit me empty! <input required>
<button>I dare you!</button>
</form>

javascript alerts refuse to work in form validation?

i keep trying everything to get these alerts to pop up correctly. i started out using nested functions, then threw them out and put it all in one function, and now when I press enter after filling out any one text box it does nothing at all, just puts the strings in the url, instead of alerting like it was before. I'm not sure if its my function call or anything else because I double checked everything and it all seems to check out to me. here is the entire code that doesnt do anything:
<html xmlns="http://www.w3.org/1999/xhtml">
<HEAD>
<TITLE>Smart Form </TITLE>
<SCRIPT LANGUAGE="JavaScript">
<!-- VARIABLE DECLARATION -->
f1.city.focus();
function check_form()
{
at_sign = email.search(/#/);
if(document.f1.city.value.length < 1)
{
alert('Please enter a city');
f1.city.focus();
}
else if(document.f1.state.value.length != 2 || !(state.charCodeAt('0')>=65 && state.charCodeAt('0')<=91))
{
alert('Please enter a state in abreviated form');
f1.state.focus();
}
else if(document.f1.zip.value.length != 5 || document.f1.zip.value.isNaN()==true)
{
alert('Please enter a 5 digit zip code');
f1.zip.focus();
}
else if((at_sign<1) || (email.length<3))
{
alert('Please enter a valid email address');
f1.email.focus();
}
else
{
document.write("Form completed");
}
}
</SCRIPT>
</HEAD>
<BODY >
<form name = "f1" action="smartform.html">
<b>City</b>
<input type = "text" name = "city" size = "18" value="" onSubmit = "javascript:check_form()">
<b>State</b>
<input type = "text" name = "state" size = "4" value="" onSubmit = "javascript:check_form()">
<b>Zip Code</b>
<input type = "text" name = "zip" size = "5" value="" onSubmit = "javascript:check_form()">
<b>Email</b>
<input type = "text" name = "email" size = "18" value="" onSubmit = "javascript:check_form()">
<input type = "submit" name = "button" value = "Done" onclick = "javascript:check_form()">
</form>
</BODY>
</HTML>
edit: nothing seems to be working that everyone says.. here is my new code:
<html xmlns="http://www.w3.org/1999/xhtml">
<HEAD>
<TITLE>Smart Form </TITLE>
<SCRIPT LANGUAGE="JavaScript">
f1.city.focus();
function check_form(f1)
{
var at_sign = f1.email.search(/#/);
if(f1.city.value.length < 1)
{
alert('Please enter a city');
f1.city.focus();
return false;
}
else if(f1.state.value.length != 2 || !(f1.state.charCodeAt('0')>=65 && state.charCodeAt('0')<=91))
{
alert('Please enter a state in abreviated form');
f1.state.focus();
return false;
}
else if((f1.zip.value.length != 5) || (f1.zip.value.isNaN()==true))
{
alert('Please enter a 5 digit zip code');
f1.zip.focus();
return false;
}
else if((at_sign<1) || (f1.email.length<3))
{
alert('Please enter a valid email address');
f1.email.focus();
return false;
}
else
{
//document.write("Form completed");
}
return false;
}
</SCRIPT>
</HEAD>
<BODY >
<form name = "f1" onSubmit="return check_form(this)">
<b>City</b>
<input type = "text" name = "city" size = "18" value="">
<b>State</b>
<input type = "text" name = "state" size = "4" value="">
<b>Zip Code</b>
<input type = "text" name = "zip" size = "5" value="">
<b>Email</b>
<input type = "text" name = "email" size = "18" value="">
<input type = "submit" name = "button" value = "Done" onclick = "return check_form(this)">
</form>
<b>hi</b>
</BODY>
</HTML>
still get no alerts... i put that hi up and got that.. but no alerts......
alright, I know I should probably be using getElementByID, but my new focus is to find out precisely why my code isn't working. Since my lecture outline examples didnt use this method, I want to figure out why the following code doesnt activate alerts like it used to. I simplified it to this:
<!DOCTYPE html>
<html>
<HEAD>
<TITLE>Smart Form </TITLE>
<SCRIPT LANGUAGE="JavaScript">
function check_form()
{
document.write("Form started");
var at_sign = document.f1.email.search(/#/);
if(document.f1.city.value.length < 1)
{
alert('Please enter a city');
document.f1.city.focus();
//return false;
}
else if(document.f1.state.value.length != 2 || !(document.f1.state.charCodeAt('0')>=65 && document.f1.state.charCodeAt('0')<=91))
{
alert('Please enter a state in abreviated form');
document.f1.state.focus();
//return false;
}
else if(document.f1.zip.value.length != 5 || isNaN(document.f1.zip.value)==true)
{
alert('Please enter a 5 digit zip code');
document.f1.zip.focus();
//return false;
}
else if((at_sign<1) || (document.f1.email.value.length<3))
{
alert('Please enter a valid email address');
document.f1.email.focus();
//return false;
}
else
{
document.write("Form completed");
}
}
</SCRIPT>
</HEAD>
<BODY onLoad= "javascript:document.f1.city.focus();">
<form name = "f1" action="smartform1.html" onSubmit="javascript:check_form();">
<b>City</b>
<input type = "text" name = "city" size = "18">
<b>State</b>
<input type = "text" name = "state" size = "4">
<b>Zip Code</b>
<input type = "text" name = "zip" size = "5">
<b>Email</b>
<input type = "text" name = "email" size = "18">
<input type = "submit" name = "button" value = "Done" onclick = "javascript:check_form();">
</form>
</BODY>
</HTML>
I get no errors in console, and now when I type something in, I get the test line "form started" to appear for a split second, along with some mysterious error, and then it all disapears and shows the form. but my question is, why doesnt an alert happen along the way to this result? it seems like even if the page got overwritten, it should still pop up. also, is there a way to pause it with code/and or debugging before it gets to the point where its overwritten? so my basic question is: why don't the alerts pop up, and how do I get the alerts to popup and the focus to remain in the correct field where the function left off within the if/else statement?
update 2: i did a quick screen cap of the errors and it turns out f1.email etc were undefined and indeed causing the thing to not work. So I still want to know how to pause it with code or in the debugger, the posts and links didnt exactly seem to be clear 100% on it. once im in the consonle and in debug mode, where exactly do i go from there to let the program pause on error?
also: if I declare the getElementByID variables at the top of my script in the header, then use them in the function, should that work without all the other event handling methods? I'm attempting this as i type.

You should put the submit listener on the form and pass a reference to the form, and return whatever value the function returns, e.g.
<form onsubmit="return check_form(this);" ...>
You should reference the controls as properties of form using their name, don't use the name as a global variable. And declare all variables.
So the function looks like:
function check_form(form) {
var at_sign = email.search(/#/);
if (form.city.value.length < 1) {
alert('Please enter a city');
f1.city.focus();
// cancel submit by returning false
return false;
} else if (form.state.value.length != 2 || !(form.state.charCodeAt(0) >=65 && state.charCodeAt(0)<=91)) {
alert('Please enter a state in abreviated form');
f1.state.focus();
return false;
}
...
}
You should probably be using a regular expression or lookup for validating the state value rather than charCodeAt.
Using document.write after the page has finished loading (e.g. when submitting the form) will erase the entire content of the page before writing the new content.
Edit
Here's what's wrong with your new code:
<SCRIPT LANGUAGE="JavaScript">
Get rid of the language attribute. It's not harmful (well, in a very specific case it might be).
f1.city.focus();
f1 has no been defined or initialised (see comments above about element names and global variables)
function check_form(f1)
{
var at_sign = f1.email.search(/#/);
f1.email is an input element, it has no search property, you can't call it. It does have a value property that is a string, perhaps you meant:
var at_sign = f1.email.value.search(/#/);
Then there is:
else if(f1.state.value.length != 2 || !(f1.state.charCodeAt('0')>=65 && state.charCodeAt('0')<=91))
again you have forgotten the value property for two of the three expressions, and forgotten to use f1 in the third. You want:
else if(f1.state.value.length != 2 || !(f1.state.value.charCodeAt(0)>=65 && f1.state.value.charCodeAt(0)<=91))
Note that this requires users to enter the state in capital letters, it might help to tell them about that.
Then there is:
else if((f1.zip.value.length != 5) || (f1.zip.value.isNaN() == true))
isNaN is a global variable, not a method of strings. If no value has been entered, then the value is the empty string and isNaN('') returns false. If you want to test that 5 digits have been entered then use:
else if (!/^\d{5}$/test(f1.zip.value))
There is no need to test against true, just use it, nor is there a need to group simple expressions:
else if (f1.zip.value.length != 5 || isNaN(f1.zip.value))
Then finally, if all the test pass:
return false;
that stops the form from submitting. You can omit this return statement, returning undefined will let the form submit. Or return true if you really want.

Ok I want to answer your question but first things first lets walk through your
code and clean it up.
Use this as a template of properly formated code:
<!DOCTYPE html>
<html>
<head>
<title>Smart Form</title>
</head>
<body>
<!-- Code goes here -->
<script type="text/javascript">
</script>
</body>
</html>
Tags & attributes don't need to be capitalized. Javascript comments are like this:
/** Comment. */
Html comments are like this:
<!-- Comment. -->
Also nitpick: attributes should be followed by an equal sign not a space. i.e.
<form name="f1" id="smartForm" action="smartform.html"> ... </form>
Next up proper event binding.
var smartForm = document.getElementById('smartForm');
smartForm.addEventListener('submit', validateForm);
Next up I'm going to teach you how to fish real quick so you can figure out why this was broken for you and how to fix these bugs in the future. Open up the developer console. Evergreen browsers (Chrome, Firefox etc...) have good ones these day. The trick you should know is how to evaluate your code so that you can see if you did something wrong or not in how you're accessing your data. So look up how to open up the developer console in your browser for your platform and type this into your console:
1+1
Should evaluate to: 2.
Next type: document
If you click around you can see that you can walk through the dom a little bit.
Next load up your smartForm app with my changes above and type:
document.getElementById('smartForm')
You should see your element. This is how to properly query objects in the dom.
You'll notice that if you type document.smartForm doesn't work. You should get null, this should tell you that there should be a way to get the element from the document. Hint, it's getElementById. So if you put id's on all your inputs then you can make a list of all the document objects you can query:
var cityElement = document.getElementById('city');
var stateElement = document.getElementById('state');
var zipElement = document.getElementById('zip');
var emailElement = document.getElementById('email');
Next you can start querying the values and such like you were doing:
cityElement.value.length != 2
A cleaned up version would look like this:
<!DOCTYPE html>
<html>
<head>
<title>Smart form</title>
</head>
<body>
<form id='smartForm' action='smartform.html'>
<b>City</b>
<input type="text" id="city" size="18">
<b>State</b>
<input type="text" id="state" size="4">
<b>Zip Code</b>
<input type="text" id="zip" size="5">
<b>Email</b>
<input type="text" id="email" size="18">
<input type="submit" value="done">
</form>
<script type="text/javascript">
var validateForm = function(evt) {
var error = false;
var cityElement = document.getElementById('city');
var stateElement = document.getElementById('state');
var zipElement = document.getElementById('zip');
var emailElement = document.getElementById('email');
if (cityElement.value.length != 2 ||
!(state.charCodeAt(0) >= 65 && state.charCodeAt(0) <= 91)) {
error = true;
alert('oops');
cityElement.focus();
}
// etc..
if (error) {
evt.preventDefault();
}
};
var smartForm = document.getElementById('smartForm');
smartForm.addEventListener('submit', validateForm);
</script>
</body>
</html>
Ok a couple more things I noticed. charCodeAt is for strings only. "hi".chatCodeAt not element.charCodeAt. Also you have this random variable at_sign.
You can save yourself a TON of time and you can learn how to diagnose where the issues are by reading this: https://developer.chrome.com/devtools/docs/console
Learning how to diagnose where the issues are is the single best skill you can learn while trying to get a grapple on javascript. I cannot emphasize this enough, learn how to debug, and you will learn how to program orders of magnitude faster. Trust me, let debugging tutorials be your bread at butter!
Full working example of your code:
http://codepen.io/JAStanton/pen/tjFHn?editors=101
A little less verbose version:
http://codepen.io/JAStanton/pen/iBJAk?editors=101

onSubmit goes in the form, not the inputs, w/o the javascript: Solved =p
<form onsubmit="return check_form();" ...
There are several mishaps in your code that might also cause errors and prevent that from working
Also, check if there are mistakes (like the HTML comment inside script), if an error happens in javascript and is untreated, all javascript in that context stops working. You can check that with any browser debugger (usually F12 will show you a window and display errors if they happen)

Script not validating name field properly

I have been setting up files to demonstrate form validation to myself. However I've found that the script doesn't check wether or not the name field is valid or not, could someone please tell me where I've went wrong?
<!DOCTYPE html>
<html>
<head>
<script>
function kValForm() {
var n = document.forms["kForm"]["kName"].value;
...
if( n == null || n == " " || n ="") {
alert("Please fill in your name.");
return false;
}
...
}
</script>
</head>
<body>
<form name="kForm" onsubmit="kValForm()">
Name: <input type="text" name="kName" placeholder="Khalifa">
<br/>
...
<br/>
<input type="submit">
</form>
</body>
</html>
The ellipses are removed bits of code that are irrelevant and take up lots of space. But the code above sends the name form even if it's empty, why?

Your form submits because you have to change your onsubmit:
<form name="kForm" onsubmit="return kValForm()">
this will prompt.
Here is a link to your modified sample that properly shows the alert: http://jsfiddle.net/bmartinelle/dyL4j49j/
(note: you need to fix your string comparison problem too - "==" instead of just one "="
Edit:
As suggested above by #Ramachandran Krishnan you can check for an empty string maybe more efficiently as elaborated in this stackoverflow post: How do you check for an empty string in JavaScript?
(note: just if(n) doesn't work)

You got an error in your if (missing ==)
if( n == null || n == " " || n ="") {
if( n == null || n == " " || n =="") {

please replace it
onsubmit="kValForm()"
by
onsubmit="return kValForm(this);

form validation javascript stop new window from opening

I have written a large page including a form as my first JavaScript project. I've gotten some help here, so thanks. I am very happy with what I have so far, but I have one last problem I need to deal with.
The code I will submit here is a tester. I have a couple of functions attached to an onClick new window. What happens is user submits form and their info appears in a new window. (My original page is more complicated, of course.) There is one function called askForHelp which shows an alert in the new window if a specific value is entered for 'state' and a very simple validateForm which shows an alert on the parent?? window if values are left blank.
The problem is b/c i have all the functions running onClick, and I realize they run concurrently, the new window opens no matter what the user does (with the alerts showing in their various places).
Based on other similar questions here, I tried adding a return false and return true statements to my conditionals, but this hasn't done anything.
Now I know there are much better ways to do what I am doing here, and that my form validation is basic and weak, but as my first foray into programming, it was very important for me to understand everything I am doing, which I do, as of now.
Can anyone show me how to fix this so the new window only opens if the form validates? I would prefer no jquery or no radical chances to the code, if possible.
I appreciate everyone's input. Here is the code:
<!doctype html>
<html>
<head>
<title>test</title>
<meta charset="utf-8">
<script type="text/javascript">
function newWindow() {
allInfo= open("", "displayWindow");
allInfo.document.open();
allInfo.document.write('<!doctype html><html><head><title>Test</title><meta charset="utf-8"></head><body>');
allInfo.document.write(document.getElementById ('state').value);
allInfo.document.write('<p>' + document.getElementById ('zip').value);
allInfo.document.write('</section></body></html>');
allInfo.document.close();
}
function askForHelp () {
var volunteer = document.getElementById('state').value;
if ((volunteer == "New York") || (volunteer == "NY") || (volunteer == "New Jersey") || (volunteer == "NJ")) {
allInfo.alert("test test test");
return false;
}
else {
return true;
}
}
function validateForm () {
var x = document.getElementById("state").value;
var y = document.getElementById("zip").value;
if (x == null || x == "" || y == null || y == "") {
alert("Please fill out the required fields.");
return false;
}
else {
return true;
}
}
</script>
</head>
<body>
<script type="text/javascript">
</script>
<form id="infoForm" method="post" name="infoForm">
<p>State: </p>
<p><input type="text" id="state" placeholder="State or Region"></p>
<p>Zip: </p>
<p><input type="text" id="zip" placeholder="Zip code" required /></p>
<p><input type="button" value="Submit Information" onClick="newWindow(), askForHelp(), validateForm()" ></p>
</form>
</body>
</html>

Instead of doing an onClick with newWindow(), askForHelp(), validateForm()
Why not just do one of them (which you want to check first) and then have the function call the others when ready?
function validateForm () {
var x = document.getElementById("state").value;
var y = document.getElementById("zip").value;
if (x == null || x == "" || y == null || y == "") {
alert("Please fill out the required fields.");
return false;
} else {
newWindow(); //Validation was successful so lets open the new window
}
}
This way you can have only validateForm() trigger on click, and the rest will trigger when they need to. You'll need to add askForHelp() inside of the newWindow function to have that trigger when necessary as well.

This is sort of a shameless plug, but I just wrote an open source JS library that attempts to solve problems like this. I call it "Is".
http://jumpkick-studios.github.io/Is/
It uses the Maybe Monad concept:
http://en.wikibooks.org/wiki/Haskell/Understanding_monads/Maybe
So it would let you solve this problem with more of a Single Responsibility Principle.
var validateState=function(obj){
return (obj.state!=null) //error check here
}
var validateZip=function(obj){
return (obj.zip!=null) //error check here
}
var openWindow=function(){
//do open window stuff
}
var handleError(){
//handle errors here
}
var onClick=function(e){
var form={state:document.getElementById("state").value, zip:document.getElementById("zip").value})
new jumpkick.Is(form)
.is(validateState)
.is(validateZip)
.then(openWindow)
.catch(handleError)
.finally(function(){
//anything else can go here
});
}
ETA: Perhaps an even better way to approach this is to not have a single handle error function, since you may want to display messaging for each wrong field.
So maybe even something like this would work (a little more code though).
var onClick=function(e){
var validInput=true;
var state=document.getElementById("state").value, zip=document.getElementById("zip").value
new jumpkick.Is(state)
.not().isLongerThan(0)
.then(function(){
validInput=false;
//display message for state
});
new jumpkick.Is(zip)
.not().isLongerThan(0)
.then(function(){
validInput=false;
//display message for zip
});
if(validInput) // openWindow
}