Script not validating name field properly - javascript

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);

Related

JavaScript - Faulty logic in simple data validation

I am super new to coding and having a difficult time with some of the logic. I asked another question last night and the community was really helpful (Thanks!), so I thought I'd try it again. `
I am trying to make an program that collects the user's email and first name. I want to check that there is something entered in each of the boxes on the form and, in order to ensure they entered their email address correctly, that emailAddress1 is the same as emailAddress2.
I have defined a "var errorMessage = "";" and if there is error at any point, it redefines a new errorMessage based on the mistake the user made on the form.
The problem, I think is with the second if-else statement. I thought that if the "errorMessage = "";" still, it would submit the form. However, no matter what it's executing the else statement and I'm getting an alert of an empty error message.
Why, if errorMessage = "", is it running the else statement and skipping over the if statement that uses errorMessage = "" as the condition?
"use strict";
var $ = function(id) {
return document.getElementById(id);
};
var joinList = function() {
var emailAddress1 = $("email_address1").value;
var emailAddress2 = $("email_address2").value;
var firstName = $("first_name").value;
var errorMessage = "";
// validate the entries
if (emailAddress1 == "") {
errorMessage = "First email address entry required";
$("email_address1").focus();
} else if (emailAddress2 == "") {
errorMessage = "Second email address entry required";
$("email_address2").focus();
} else if (emailAddress2 != emailAddress1) {
errorMessage = "Email address entries must match";
$("email_address2").focus();
} else if (firstName == "") {
errorMessage = "First name entry required";
$("first_name").focus();
}
// submit the form if all entries are valid
// otherwise, display an error message
if (errorMessage = "") {
$("email_form").submit();
} else {
alert(errorMessage);
}
};
window.onload = function() {
$("join_list").onclick = joinList;
$("email_address1").focus();
};
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title> Join Email List</title>
<link rel="stylesheet" href="email_list.css">
<script src="email_list.js"></script>
</head>
<body>
<main>
<h1>Please join our email list</h1>
<form id="email_form" name="email_form" action="join.html" method="get">
<label for="email_address1">Email Address:</label>
<input type="text" id="email_address1" name="email_address1"><br>
<label for="email_address2">Re-enter Email Address:</label>
<input type="text" id="email_address2" name="email_address2"><br>
<label for="first_name">First Name</label>
<input type="text" id="first_name" name="first_name"><br>
<label> </label>
<input type="button" id="join_list" value="Join our List">
</form>
</main>
</body>
</html>
**
So you have a typo in your code where you are not comparing, you are setting the variable equal to an empty string. And an empty string is a falsy value
So your code is basically this
errorMessage = "";
if (errorMessage) {
} else {
}
Using a tool like jshint, jslint, eslint, etc build into your IDE will help you catch these typos. So alter your code to do the correct comparison.
if (errorMessage === "") {
I'm not sure if you can extract values form inputs this way.
email_address1 is element id so you must refer to it with hashtag on the beginning.
Proper way in jQuery to do this $("#email_address1").val()
Difference between =, == and === is quite important.
let testVariable = 123; // only assigns value to a variable
Difference between = and == is quite obvious. Between == and === is little bit more complicated.
== operator compares only values and does not recognize data types but === recognizes them. What it means to to you?
Lets say than you have variable testNumber with assigned value 123 as a number and variable textText with assigned value "123"(notice the quotes).
If you compare them with == expression returns true but if you compare them with === expression returns false.
let testNumber = 123;
let testText = "123";
As you can see variable testText is in doublequotes which means it's datatype is String. String is just normal text. But testNumber variable has datatype Integer. Integer is just normal number. Content of these two variables does not differ but datatypes does.
testNumber == testText //true - same content, different datatype we ignore that
testNumber === testTExt // false - same content, different datatype but now we consider it
I hope I helped you at least a little bit. :)
Edit: Also i suggest you to open developer tools(F12) in chrome and check console. You can see errors in there. It helps you a lot.

How to convert input to string and find the index of the first two characters?

This is my first time posting here since I haven't been able to find a specific answer for my question anywhere so apologies if I'm doing something wrong.
Anyway, I wanted to know if there was a way to convert text from a form input to a string and grab a substring of that text?
For example if I have a form input like this:
<form onsubmit="return formValidation()">
<input type="text" name="foo">
</form>
Can I grab whatever is typed into that input like so?
function myFunction() {
var string = document.getElementByName('foo').value;
// Code converting the selected element to a string
var index = string.substring(0, 2);
// Rest of code
}
I have little experience in JavaScript so I'm confused on how to convert an element to string. jQuery solutions are welcome.
I wanted to do this for an ID number validation on a form, which basically checks the first two indexes of an 8-digit ID number to see if it's a known ID number in my school district.
Thanks!
EDIT:
Okay so since people actually saw this, could anyone tell me what's wrong with this code? It's returning false even for numbers starting with the numbers here.
function formValidation() {
var idInput = document.getElementsByName('idNumber')[0].value;
var idNumber = idInput.substring(0, 2);
if(idNumber === "71" || idNumber === "81" || idNumber === "53") {
alert("Your form has been submitted. You will now be redirected to a confirmation page.");
return true;
} else {
alert("Please input a valid ID number. If the first two integers of your ID do not match the school district standard, contact a club leader.");
return false;
}
}
Is the method I'm using to compare strings wrong?
Problem is: document.getElementByName('foo').value, you have missed s
document.getElementsByName('foo')
^
document.getElementsByName('foo') gives you NodeList, not just a single HtmlElement,
Use instead:
document.getElementsByName('foo')[0].value;
Edited: Have a look at below functional code.
function formValidation() {
var idInput = document.getElementsByName('idNumber')[0].value;
var idNumber = idInput.substring(0, 2);
if (idNumber === "71" || idNumber === "81" || idNumber === "53") {
alert("Your form has been submitted. You will now be redirected to a confirmation page.");
return true;
} else {
alert("Please input a valid ID number. If the first two integers of your ID do not match the school district standard, contact a club leader.");
return false;
}
}
<form onsubmit="return formValidation();">
<input type="text" name="idNumber" autofocus="" value="71456" maxlength="8" />
</form>

Javascript form validation, what is missing?

I can't get a form to validate no matter what I try, so I have dumbed it down alot to see if I could get ANYTHING to work, and still when I submit the form the javascript does not validate, and simply sends me to the next page no matter what. You guys see anything wrong??
HTML
<form id="myform" action="/" method="post" onsubmit="return Validate()">
<input id="form_name" type="text" name="name" placeholder="Name" />
<div id="error">Name too short</div>
<input type="submit" id="submit" name="submit" value="Enter" />
JAVASCRIPT IN HEAD
<script language="JavaScript" type="text/javascript">
function Validate() {
if (form.name.value == "") {
$('#error').show();
return false ;
}
return true ;
}
</script>
And in the CSS I have the display for the #error div set to none.
Ultimately I want to check that the user entered at least 4 characters in the text input field, if they didnt then I don't want the form submitted but rather show the error message. But for now I'm just checking to see if its empty to see if I can get anything to work. Any ideas?
First of all remove language from the script tag, it's deprecated.
Then you should not load your script in the head section. Instead put it where body ends to ensure that the HTML has loaded.
Also in your validate function you don't seem to actually target the correct ID's.
Use this:
function Validate() {
if ($('#form_name').val() === '') {
$('#error').show();
return false ;
}
return true ;
}
Replace your javascript for this
function Validate() {
// Use form_name instead of form.name
if (form_name.value == "") {
// This line will break if you do not have jquery.
$('#error').show();
return false ;
}
return true ;
}
Define IDs for tags and use jQuery to get those tags and check their values. For example, if the name tag had id="form_name" you could do something like this:
if ($("#form_name").val() == ""))
$('#error').show();
On the other hand, I recommend you to check jQuery Validate plug-in which is great for validating forms:
http://jqueryvalidation.org/
Instead of
if (form.name.value == "") {
use:
var nameField=document.getElementById("form_name");
if (nameField.value == "") {
Let me know if this works.

Javascript can't locate HTML form ID

I'm creating a basic HTML form, and a Javascript form validator that looks for any input value in the "first name" field. The problem I'm having is that nothing seems to be working to return the first name form value to check it in JS.
Relevant HTML:
<form id="form1" name="formName">
First name:<br>
<input type="text" id="fn" >
<br>
Last name:<br>
<input type="text" name="ln" >
<br>
Email address: <span style="color:red">(required)</span><br>
<input type="text" name="email" >
<br><br>
<button onclick="validate()">Submit</button>
</form>
My JS:
var validate = function (){
var x = document.getElementById("fn").value;
if (x == null || "" || "undefined"){
alert("Please fill out your first name");
return false;
}
kickoff();
}
var kickoff = function () {
var visitor = document.forms["form1"].fn.value;
alert("Thanks for filling out, " + visitor +"\n");
return visitor;
};
Here's a JSFiddle.
My X variable is never reached, it seems, and keeps returning "undefined" when I submit the page. I've been fiddling with it for quite a while and can't seem to figure out what I'm doing wrong. Any help?
This doesn't mean what you think:
if (x == null || "" || "undefined") {
Can also be written as:
if ((x == null) || // might be false
"" || // will be false
"undefined" // will be true
) {
so the if will always be true.
You really just need:
if (! x) {
Besides the syntax issues, that method is also out-of-scope. You're not even going to be able to debug the issue with your conditional until you fix that.
You can either in-line the script higher up in the DOM or define validate directly on the window object:
window.validate = function () {
http://jsfiddle.net/frg37t3u/5/
Neither case is ideal, you should know. Globals are bad, but that's another discussion.

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)

Categories