Develop Reference

How do you validate multiple radio buttons at one time without jQuery?

I am writing a validation function for a html code that was given to me for my class, but am not allowed to change the html code besides adding a head and script. I am at such an early stage that I don't know how to use jQuery yet and would like help with validation for the multiple radio buttons.
I have tried looking for the answer on this and many other sites and just can't seem to find it. I have tried multiple codes, but I suspect that all of them were made with jQuery.
The input for the html
<input type = "radio" name = "radNewsletter" value = "" />Health and Wellness<br />
<input type = "radio" name = "radNewsletter" value = "" />Creative Writing<br />
<input type = "radio" name = "radNewsletter" value = ""/>Gardening
The existing validation
function validateForm() {
var x = document.forms["frmNews"]["txtName"].value;
if (x == "") {
alert ("Name must be filled out.");
return false;
}
var y = document.forms["frmNews"]["txtEmail"].value;
if (y == "") {
alert ("Email must be filled out.");
return false;
}
I was unable to get any other output than the form validating when I pressed the submit button, even when the existing validation should have stopped it.

I found that radNewsletter is a common name in your form. In order to validate forms for radio buttons, you can use below code.
function validateForm() {
var radios = document.getElementsByName("radNewsletter");
var formValid = false;
var i = 0;
while (!formValid && i < radios.length) {
if (radios[i].checked) formValid = true;
i++;
}
if (!formValid) alert("Must check some option!");
console.log(formValid)
return formValid;
}
<input type = "radio" name = "radNewsletter" value = "" />Health and Wellness<br />
<input type = "radio" name = "radNewsletter" value = "" />Creative Writing<br />
<input type = "radio" name = "radNewsletter" value = ""/>Gardening
<br />
<button onclick="validateForm()">Validate
</button>

function validateForm() {
var radios = document.getElementsByName("radNewsletter");
if(!radios.checked)
{
alert("we are testing")
}
if(radios.checked = true){
alert("your checking the boxs")
}
}

Use document.querySelector and pusedo selector checked. This line document.querySelector('input[name="radNewsletter"]:checked') will give the first radio button with the name radNewsletter which is checked. On click of button check if this value is not null. Hopefully you can validate using this
function validate() {
let isChecked = document.querySelector('input[name="radNewsletter"]:checked');
if (isChecked !== null) {
console.log(isChecked.value);
}
}
<input type="radio" name="radNewsletter" value="hw">Health and Wellness<br />
<input type="radio" name="radNewsletter" value="cw">Creative Writing<br />
<input type="radio" name="radNewsletter" value="g">Gardening<br/>
<button type='button' onclick='validate()'>Validate</button>

enabling a button when checkbox is checked?

I have a scenario on my UI where I need to enable a text box and a button on checking a checkbox and disable both text box and the button when the checkbox is un-checked. Below is the screenshot of what I have:
Below is the code in my jsp:
<tr>
<td>
<stripes:checkbox name="locationselect" onclick="handleDisable(document.forms['dealerTransactionForm'].elements['locationselect'],document.forms['dealerTransactionForm'].elements['locationId'])"/>
<stripes:label for="locationId"/>
</td>
<td>
<stripes:text name="locationId" />
<fmt:message var="tooltip" key="/DealerTransactionReport.action.lookUpLocation"/>
<stripes:submit name="lookUpLocation" class="button" title="${tooltip}" style="width: auto"/>
</td>
</tr>
Below is the handleDisable function which I wrote:
function handleDisable(checkbox, item) {
if(checkbox.checked == true)
item.disabled = false;
else
item.disabled = true;
}
Currently I'm able to enable only the text box when the checkbox is checked, what change should i make so as to enable both the text box and the button?.

You need to pass in a third parameter to the function for your button. You are only passing in the checkbox and the text box.
HTML:
<stripes:checkbox name="locationselect" onclick="handleDisable(document.forms['dealerTransactionForm'].elements['locationselect'],document.forms['dealerTransactionForm'].elements['locationId'], document.forms['dealerTransactionForm'].elements['lookUpLocation'])"/>
JavaScript:
function handleDisable(checkbox, text, button)
{
if(checkbox.checked == true) {
text.disabled = false;
button.disabled = false;
}
else {
text.disabled = true;
button.disabled = true;
}
}
But that makes the html too busy, in my opinion. I would opt for something like this.
HTML:
<stripes:checkbox name="locationselect" onclick="handleDisable(this)"/>
JavaScript:
function handleDisable(checkbox)
{
var text = document.getElementsByName("locationId")[0]
var button = document.getElementsByName("lookupLocation")[0]
if(checkbox.checked == true) {
text.disabled = false;
button.disabled = false;
}
else {
text.disabled = true;
button.disabled = true;
}
}

Using jQuery you can do it like following.
$('name="locationselect"').change(function() {
$('name="locationId"').prop('disabled', !this.checked);
});
UPDATE: Since the jQuery tag is removed
<script>
function handleDisable(elm) {
document.getElementsByName('locationId')[0].disabled = !elm.checked;
document.getElementsByName('lookUpLocation')[0].disabled = !elm.checked;
}
</script>
<input type="checkbox" name="locationselect" onclick="handleDisable(this)" />
<input type="text" name="locationId" disabled>
<input type="submit" value="Submit" name="lookUpLocation" disabled>

Validating a checkbox after already validating other sections of a form [duplicate]

I have a form with multiple checkboxes and I want to use JavaScript to make sure at least one is checked. This is what I have right now but no matter what is chosen an alert pops up.
JS (wrong)
function valthis(){
if (document.FC.c1.checked) {
alert ("thank you for checking a checkbox")
} else {
alert ("please check a checkbox")
}
}
HTML
<p>Please select at least one Checkbox</p>
<br>
<br>
<form name = "FC">
<input type = "checkbox" name = "c1" value = "c1"/> C1
<br>
<input type = "checkbox" name = "c1" value = "c2"/> C2
<br>
<input type = "checkbox" name = "c1" value = "c3"/> C3
<br>
<input type = "checkbox" name = "c1" value = "c4"/> C4
<br>
</form>
<br>
<br>
<input type = "button" value = "Edit and Report" onClick = "valthisform();">
So what I ended up doing in JS was this:
function valthisform(){
var chkd = document.FC.c1.checked || document.FC.c2.checked||document.FC.c3.checked|| document.FC.c4.checked
if (chkd == true){
} else {
alert ("please check a checkbox")
}
}
I decided to drop the "Thank you" part to fit in with the rest of the assignment. Thank you so much, every ones advice really helped out.

You should avoid having two checkboxes with the same name if you plan to reference them like document.FC.c1. If you have multiple checkboxes named c1 how will the browser know which you are referring to?
Here's a non-jQuery solution to check if any checkboxes on the page are checked.
var checkboxes = document.querySelectorAll('input[type="checkbox"]');
var checkedOne = Array.prototype.slice.call(checkboxes).some(x => x.checked);
You need the Array.prototype.slice.call part to convert the NodeList returned by document.querySelectorAll into an array that you can call some on.

This should work:
function valthisform()
{
var checkboxs=document.getElementsByName("c1");
var okay=false;
for(var i=0,l=checkboxs.length;i<l;i++)
{
if(checkboxs[i].checked)
{
okay=true;
break;
}
}
if(okay)alert("Thank you for checking a checkbox");
else alert("Please check a checkbox");
}
If you have a question about the code, just comment.
I use l=checkboxs.length to improve the performance. See http://www.erichynds.com/javascript/javascript-loop-performance-caching-the-length-property-of-an-array/

I would opt for a more functional approach. Since ES6 we have been given such nice tools to solve our problems, so why not use them.
Let's begin with giving the checkboxes a class so we can round them up very nicely.
I prefer to use a class instead of input[type="checkbox"] because now the solution is more generic and can be used also when you have more groups of checkboxes in your document.
HTML
<input type="checkbox" class="checkbox" value=ck1 /> ck1<br />
<input type="checkbox" class="checkbox" value=ck2 /> ck2<br />
JavaScript
function atLeastOneCheckboxIsChecked(){
const checkboxes = Array.from(document.querySelectorAll(".checkbox"));
return checkboxes.reduce((acc, curr) => acc || curr.checked, false);
}
When called, the function will return false if no checkbox has been checked and true if one or both is.
It works as follows, the reducer function has two arguments, the accumulator (acc) and the current value (curr). For every iteration over the array, the reducer will return true if either the accumulator or the current value is true.
the return value of the previous iteration is the accumulator of the current iteration, therefore, if it ever is true, it will stay true until the end.

Check this.
You can't access form inputs via their name. Use document.getElements methods instead.

Vanilla JS:
var checkboxes = document.getElementsByClassName('activityCheckbox'); // puts all your checkboxes in a variable
function activitiesReset() {
var checkboxesChecked = function () { // if a checkbox is checked, function ends and returns true. If all checkboxes have been iterated through (which means they are all unchecked), returns false.
for (var i = 0; i < checkboxes.length; i++) {
if (checkboxes[i].checked) {
return true;
}
}
return false;
}
error[2].style.display = 'none'; // an array item specific to my project - it's a red label which says 'Please check a checkbox!'. Here its display is set to none, so the initial non-error label is visible instead.
if (submitCounter > 0 && checkboxesChecked() === false) { // if a form submit has been attempted, and if all checkboxes are unchecked
error[2].style.display = 'block'; // red error label is now visible.
}
}
for (var i=0; i<checkboxes.length; i++) { // whenever a checkbox is checked or unchecked, activitiesReset runs.
checkboxes[i].addEventListener('change', activitiesReset);
}
Explanation:
Once a form submit has been attempted, this will update your checkbox section's label to notify the user to check a checkbox if he/she hasn't yet. If no checkboxes are checked, a hidden 'error' label is revealed prompting the user to 'Please check a checkbox!'. If the user checks at least one checkbox, the red label is instantaneously hidden again, revealing the original label. If the user again un-checks all checkboxes, the red label returns in real-time. This is made possible by JavaScript's onchange event (written as .addEventListener('change', function(){});

You can check that atleast one checkbox is checked or not using this simple code. You can also drop your message.
Reference Link
<label class="control-label col-sm-4">Check Box 2</label>
<input type="checkbox" name="checkbox2" id="checkbox2" value=ck1 /> ck1<br />
<input type="checkbox" name="checkbox2" id="checkbox2" value=ck2 /> ck2<br />
<script>
function checkFormData() {
if (!$('input[name=checkbox2]:checked').length > 0) {
document.getElementById("errMessage").innerHTML = "Check Box 2 can not be null";
return false;
}
alert("Success");
return true;
}
</script>

< script type = "text/javascript" src = "js/jquery-1.6.4.min.js" > < / script >
< script type = "text/javascript" >
function checkSelectedAtleastOne(clsName) {
if (selectedValue == "select")
return false;
var i = 0;
$("." + clsName).each(function () {
if ($(this).is(':checked')) {
i = 1;
}
});
if (i == 0) {
alert("Please select atleast one users");
return false;
} else if (i == 1) {
return true;
}
return true;
}
$(document).ready(function () {
$('#chkSearchAll').click(function () {
var checked = $(this).is(':checked');
$('.clsChkSearch').each(function () {
var checkBox = $(this);
if (checked) {
checkBox.prop('checked', true);
} else {
checkBox.prop('checked', false);
}
});
});
//for select and deselect 'select all' check box when clicking individual check boxes
$(".clsChkSearch").click(function () {
var i = 0;
$(".clsChkSearch").each(function () {
if ($(this).is(':checked')) {}
else {
i = 1; //unchecked
}
});
if (i == 0) {
$("#chkSearchAll").attr("checked", true)
} else if (i == 1) {
$("#chkSearchAll").attr("checked", false)
}
});
});
< / script >

Prevent user from deselecting last checked checkbox.
jQuery (original answer).
$('input[type="checkbox"][name="chkBx"]').on('change',function(){
var getArrVal = $('input[type="checkbox"][name="chkBx"]:checked').map(function(){
return this.value;
}).toArray();
if(getArrVal.length){
//execute the code
$('#msg').html(getArrVal.toString());
} else {
$(this).prop("checked",true);
$('#msg').html("At least one value must be checked!");
return false;
}
});
UPDATED ANSWER 2019-05-31
Plain JS
let i,
el = document.querySelectorAll('input[type="checkbox"][name="chkBx"]'),
msg = document.getElementById('msg'),
onChange = function(ev){
ev.preventDefault();
let _this = this,
arrVal = Array.prototype.slice.call(
document.querySelectorAll('input[type="checkbox"][name="chkBx"]:checked'))
.map(function(cur){return cur.value});
if(arrVal.length){
msg.innerHTML = JSON.stringify(arrVal);
} else {
_this.checked=true;
msg.innerHTML = "At least one value must be checked!";
}
};
for(i=el.length;i--;){el[i].addEventListener('change',onChange,false);}
<label><input type="checkbox" name="chkBx" value="value1" checked> Value1</label>
<label><input type="checkbox" name="chkBx" value="value2"> Value2</label>
<label><input type="checkbox" name="chkBx" value="value3"> Value3</label>
<div id="msg"></div>

$('input:checkbox[type=checkbox]').on('change',function(){
if($('input:checkbox[type=checkbox]').is(":checked") == true){
$('.removedisable').removeClass('disabled');
}else{
$('.removedisable').addClass('disabled');
});

if(($("#checkboxid1").is(":checked")) || ($("#checkboxid2").is(":checked"))
|| ($("#checkboxid3").is(":checked"))) {
//Your Code here
}
You can use this code to verify that checkbox is checked at least one.
Thanks!!

Enable/disable button based on accepting the 2 checkbox conditions

I have gone through the stackoverflow regarding enable/disable button conditionally and was able to find some help but NOT EXACT what I was looking for.
Instead of 1 checkbox condition, I have 2 checkbox conditions. So unless if the two checkboxes have been accepted, the button should not be enabled.
Following is my html:
<input type="checkbox" id="f_agree" value="1" onchange="checked(this, 'f_agree2')"/>
<input type="checkbox" id="f_agree2" value="1" onchange="checked('f_agree', this)"/>
<button type="submit" disabled="disabled" id="acceptbtn">Continue</button>
Following is javascript:
function checked(element1, element2) {
var myLayer = document.getElementById('acceptbtn');
if (element1.checked == true && element2.checked == true) {
myLayer.class = "submit";
myLayer.disabled = "";
} else {
myLayer.class = "button:disabled";
myLayer.disabled = "disabled";
};
}
I have tried like above, but it is not working. I don't know where I am going wrong.

it won't work because you are not removing that attribute disabled.
function checked(element1, element2) {
var myLayer = document.getElementById('acceptbtn');
if (element1.checked == true && element2.checked == true) {
myLayer.class = "submit";
myLayer.removeAttribute("disabled");
} else {
myLayer.class = "button:disabled";
myLayer.setAttribute("disabled","disabled");
};
}
Update
use any other name then checked as it seems to be reserved and not working.
you also need to do getElementById for element1 and element2.
function checkedFunc(element1Id, element2Id) {
var myLayer = document.getElementById('acceptbtn');
var element1 = document.getElementById(element1Id);
var element2 = document.getElementById(element2Id);
if (element1.checked == true && element2.checked == true) {
myLayer.class = "submit";
myLayer.removeAttribute("disabled");
} else {
myLayer.class = "button:disabled";
myLayer.setAttribute("disabled","disabled");
};
}
<input type="checkbox" id="f_agree" value="1" onchange="checkedFunc('f_agree', 'f_agree2')"/>
<input type="checkbox" id="f_agree2" value="1" onchange="checkedFunc('f_agree','f_agree2')"/>
<input type="button" value="check" id="acceptbtn" />

You can try the following code
if (element1.checked == true && element2.checked == true) {
myLayer.class = "submit";
myLayer.removeAttribute("disabled");
} else {
myLayer.class = "button:disabled";
myLayer.setAttribute("disabled", "disabled");
};

With jQuery:
var btn;
var changed = function() {
//get the length of non checked boxes
var disbl = $('input[id^=f_agree]:not(:checked)').length;
btn.prop('disabled', disbl);//disable if true, else enable
};
$(function() {
btn = $('#acceptbtn');
$('input[id^=f_agree]').on('change', changed).trigger('change');
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<input type="checkbox" id="f_agree" value="1" />1
<input type="checkbox" id="f_agree2" value="1" />2
<input type="button" id="acceptbtn" value="Submit" />

The problem is that there is a difference between the string "f_agree" and the node with id="f_agree".
Your code should work as expected with
checked(this, document.getObjectById('f_agree2'))
Much better would be however to avoid having a widget knowing about the other... I'd implement instead by adding a list of external rules that check all widgets:
function okSubmit() {
return (document.getElementById("f_agree").checked &&
document.getElementById("f_agree2").checked);
}
This is much easier to read/maintain and also scales better in case you need to add more conditions later. In the onchange of all the widgets just call a function that will enable/disable the submit button depending on the conditions.

Try this
if (element1.checked == true && element2.checked == true) {
myLayer.class = "submit";
myLayer.removeAttribute("disabled");
} else {
myLayer.class = "button:disabled";
myLayer.setAttribute("disabled", "disabled");
};

Try the below code -
var chk1 = document.getElementById('chk1');
chk1.addEventListener('click', checked, false);
var chk2 = document.getElementById('chk2');
chk2.addEventListener('click', checked, false);
function checked(){
if(chk1.checked && chk2.checked) {
document.getElementById('btn').removeAttribute('disabled');
} else {
document.getElementById('btn').setAttribute('disabled','disabled');
}
}
<input type="checkbox" id="chk1" />
<input type="checkbox" id="chk2" />
<button id="btn" disabled >Button<button>
I tested it and it's working! Hope it helps u...

How do I properly validate the form using input radios?

I have a problem with validating the form in function validate() method. This line of code:
if(radios[i].value == "yes" && radios[i].checked == true) //DEBUG INFO: skips this step to else.
is being skipped because one or both of the conditions are false, but I'm not sure which one and as well as if the condition is proper to execute. I was thinking that radios[i].value == "yes" will correspond to the value attribute of that input radio button (In other words, the correct answer regarding that question).
When the submit button is clicked, I simply want javascript to tell me whether it's correct or not and to check if the radio button is checked.
Problem: I checked in the radio button, when submit button is clicked the alert for Please make sure you answer every question pops up 3 times and after that displays that I have the correct answer.
Here's the full code:
JavaScript:
// called when "Take Quiz" button is clicked
function takeQuiz()
{
// hide the intro
document.getElementById('intro').style.display = 'none';
// display the quiz
document.getElementById('message').style.overflow = 'auto';
document.getElementById('quiz').style.visibility = 'visible';
document.getElementById('gl_banner').style.display = 'block';
document.getElementById('gl_banner').style.visibility = 'visible';
}
//document.getElementById('submit').onclick = validateQuiz; //calls the function "validateQuiz" when submit button is clicked
// check for validation in the quiz
function validateQuiz()
{
var radios; // access elements by object name (DOM)
var i; // int variable
var right; // boolean variable to determine correct answer
radios = document.getElementById('question1').getElementsByTagName('input');
/*radios = document.getElementById('question2').getElementsByTagName('input');
radios = document.getElementById('question3').getElementsByTagName('input');
radios = document.getElementById('question4').getElementsByTagName('input');
radios = document.getElementById('question5').getElementsByTagName('input');*/
right = true;
// loop to check each radio button for validation
for(i = 0; i < radios.length; i++)
{
if(radios[i].value == "yes" && radios[i].checked == true) //DEBUG INFO: skips this step to else.
{
right = true;
}
else if(radios[i].checked == false)
{
right = false;
alert("Please check to make sure you have answered every question.");
}
}
if(right)
{
alert("You have answered correctly!");
}
else
{
alert("Wrong answer");
}
}
HTML Code:
<div id="message" style="overflow:hidden;"><div id="intro">Why not go ahead and take the quiz to test your knowledge based on what you've learned in Smartphone Photography.
There are only 5 questions surrounding the content of this site.
<br/>
<button id="takeQuiz" type="button" name="name" onclick="takeQuiz()" style="cursor:pointer;">Take Quiz!</button></div>
<div id="gl_banner" style="display:none; visibility:hidden;">Good Luck! :)</div>
<form id="quiz" action="#" method="post" style="visibility:hidden;" autocomplete="off">
<!--QUIZ-->
<h3>1. How many percent of modern camera phones use CMOS?</h3>
<div id="question1">
<input type="radio" name="question-1-answers" id="question-1-answers-A" value="A" />
<label for="question-1-answers-A">A) 20%</label>
<br/>
<input type="radio" name="question-1-answers" id="question-1-answers-B" value="B" />
<label for="question-1-answers-B">B) 80%</label>
<br/>
<input type="radio" name="question-1-answers" id="question-1-answers-C" value="C" />
<label for="question-1-answers-C">C) 50%</label>
<br/>
<input type="radio" name="question-1-answers" id="question-1-answers-D" value="yes" />
<label for="question-1-answers-D">D) 90%</label>
</div>

**Edited for a pure javascript solution.
I got the function to get the select value from this post.
I don't think you need to do a loop here, as you only actually need to check one value- the value of the checked radio.
At the moment your looping through all the radios, so you'll always get three wrong answers.
**Edited again to fix some code errors. I have tested the following, it is working for me.
function getRadioValue(name) {
var group = document.getElementsByName(name);
for (var i=0;i<group.length;i++) {
if (group[i].checked) {
return group[i].value;
}
}
return '';
}
document.getElementById('submit').onclick = validateQuiz; //calls the function "validateQuiz" when submit button is clicked
// check for validation in the quiz
function validateQuiz(){
right = true;
radio = getRadioValue("question-1-answers");
if(!radio.length) {
right = false;
alert("Please check to make sure you have answered every question.");
return;
}
if(radio == 'yes')
{
alert("You have answered correctly!");
}
else {
right = false;
alert("Wrong answer");
}
}