Error updating CSS using JQuery .change() with multiple radio inputs - html

I am having an error where my JQuery works initially upon radio click, but after toggling the radio buttons a few times, it breaks.
What is the proper way to update page text in CSS with 2+ radio questions using JQuery? The toggling of the multiple radio buttons (upon user click) should work indefinitely as it's a simple, basic if condition.
Code:
var q1 = $("input[name=q1]:radio");
var q2 = $("input[name=q2]:radio");
var q3 = $("input[name=q3]:radio");
var a1 = "foo";
var a2 = "bar";
var aa = "bas";
q1.change(function () {
$("input:checked").each(
function () {
if ($(this).val() == "Yes") {
$("#a1").text(a1);
} else {
$("#a1").text("");
};
}
);
})
q2.change(function () {
$("input:checked").each(
function () {
if ($(this).val() == "Yes") {
$("#a2").text(a2);
} else {
$("#a2").text("");
};
}
);
})
.change();
HTML
Question 1 Here?<br />
<input type="radio" name="q1" id="q1-y" value="Yes" />Yes
<input type="radio" name="q1" id="q1-n" value="No" />No
<br />
Question 2 Here?<br />
<input type="radio" name="q2" id="q2-y" value="Yes" />Yes
<input type="radio" name="q2" id="q2-n" value="No" />No
<br />
Question 3 Here?<br />
<input type="radio" name="q3" id="q3-y" value="Yes" />Yes
<input type="radio" name="q3" id="q3-n" value="No" />No
<div id="a1"></div>
<div id="a2"></div>
<div id="a3"></div>
<div id="aa"></div>
I'd like to insert text into the Divs based on what is checked in the radio buttons. As mentioned above, the JQuery appears to work initially, but after 3+ clicks, the if statements don't work.
Thanks

The problem lies in these lines:
$("input:checked").each(
This means the condition of every checked input is being used to determine what should be displayed, when it should only be one set of radio buttons informing the decision. The problem doesn't appear until multiple radio button sets have been checked. A quick fix is to say:
q1.change(function () {
$("input[name=q1]:checked").each(
and similarly for each change handler.
DEMO

Related

jQuery change innerHtml of a group of radio buttons labels with a onClick listener using data-target

I have multiple groups of radio buttons. Names and Id's dynamically via variables. Each radio button has a label that I use (via css) as a button instead of the radio button itself (hidden).
when I click on a label, I need two things to happen:
all labels in that group of radio buttons to have their innerHtml reset to xxxx
the clicked labels innerHtml set to yyyy
The second part I can do. Its the first part I have trouble with. Maybe there is need to do it as a loop? But anyway, tried it with a single radio button first, couldn't make it work
$(document).on('click', '.n', function() {
$('label[for^=$(this).data("target")]').html("xxxx");
$("#" + $(this).data("target") + "label").html("yyyy");
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="radio" id="1" name="na" value="" />
<label for="1" data-target="1" id="1label" class="n" selected>yyyy</label>
<input type="radio" id="2" name="na" value="" />
<label for="2" data-target="2" id="2label" class="n">xxxx</label>
<input type="radio" id="3" name="na" value="" />
<label for="3" data-target="3" id="3label" class="n">xxxx</label>
Please check below, hope it is clear:
$(document).on('click', '.n', function() {
var thisLabel = $(this);
var thisDataTarget = thisLabel.data('target');
var thisTarget = $('#'+thisDataTarget);
var thisGroupName = thisTarget.attr('name');
$('input[name='+thisGroupName+']').each(function(i) {
var loopInput = $(this);
var loopID = loopInput.attr('id');
var loopText = loopID==thisDataTarget ? 'yyyy' : 'xxxx';
$('label[for='+loopID+']').html( loopText );
});
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="radio" id="1" name="na" value="" />
<label for="1" data-target="1" id="1label" class="n" selected>yyyy</label>
<input type="radio" id="2" name="na" value="" />
<label for="2" data-target="2" id="2label" class="n">xxxx</label>
<input type="radio" id="3" name="na" value="" />
<label for="3" data-target="3" id="3label" class="n">xxxx</label>
Also on JSFiddle.
I hope I understood your question correctly and solved it with this code snippet:
// loop over all labels
$('label').each(function () {
// add onclick listeners to all labels
$(this).on('click', function () {
// set each label's innerhtml to xxxx
$('label').each(function () {
$(this).html('xxxx')
})
// set currently clicked label's innerhtml to yyyy
$(this).html('yyyy')
})
})
Example: https://codepen.io/SubhumanWasTaken/pen/MWKZPrb

How to make specific radio button in HTML5 with automatically selecting Specify while manually adding data

I am working on a web interface for taking inputs in such a way that imagine there are three radio buttons with specific functions,and one of radio input function also has number input along with it. Take a look at example:
<h2>How many cars you own?</h2>
<form>
<input type="radio" name="car" checked>One<br>
<input type="radio" name="car">Two<br>
<input type="radio" name="car">Specify
<input type="number" name="car"><br>
</form>
Actually this works, but I want my website to be a little more smart and dynamic, so the main problem is the moment I select a number from Choose, it should automatically mark the Specify radio button, but it doesn't.And if I am choosing One or Two as my choice, it should disable the number input with a blank interface.
I think you want something like this
var cars = document.getElementsByName("car");
cars[3].addEventListener("input", function(e) {
if (e.target.value < 1) {
e.target.value = 1;
}
if (e.target.value === 1) {
cars[2].checked = true;
} else {
cars[e.target.value - 1].checked = true;
}
});
<h2>How many cars you own?</h2>
<form>
<input type="radio" name="car" checked>One<br>
<input type="radio" name="car">Two<br>
<input type="radio" name="car">Specify
<input type="number" name="car" value="1"><br>
</form>

minimum one required for checkboxes with same name [duplicate]

When using the newer browsers that support HTML5 (FireFox 4 for example);
and a form field has the attribute required='required';
and the form field is empty/blank;
and the submit button is clicked;
the browsers detects that the "required" field is empty and does not submit the form; instead browser shows a hint asking the user to type text into the field.
Now, instead of a single text field, I have a group of checkboxes, out of which at least one should be checked/selected by the user.
How can I use the HTML5 required attribute on this group of checkboxes?
(Since only one of the checkboxes needs to be checked, I can't put the required attribute on each and every checkbox)
ps. I am using simple_form, if that matters.
UPDATE
Could the HTML 5 multiple attribute be helpful here? Has anyone use it before for doing something similar to my question?
UPDATE
It appears that this feature is not supported by the HTML5 spec: ISSUE-111: What does input.#required mean for #type = checkbox?
(Issue status: Issue has been marked closed without prejudice.)
And here is the explanation.
UPDATE 2
It's an old question, but wanted to clarify that the original intent of the question was to be able to do the above without using Javascript - i.e. using a HTML5 way of doing it. In retrospect, I should've made the "without Javascript" more obvious.
Unfortunately HTML5 does not provide an out-of-the-box way to do that.
However, using jQuery, you can easily control if a checkbox group has at least one checked element.
Consider the following DOM snippet:
<div class="checkbox-group required">
<input type="checkbox" name="checkbox_name[]">
<input type="checkbox" name="checkbox_name[]">
<input type="checkbox" name="checkbox_name[]">
<input type="checkbox" name="checkbox_name[]">
</div>
You can use this expression:
$('div.checkbox-group.required :checkbox:checked').length > 0
which returns true if at least one element is checked.
Based on that, you can implement your validation check.
Its a simple trick. This is jQuery code that can exploit the html5 validation by changing the required properties if any one is checked. Following is your html code (make sure that you add required for all the elements in the group.)
<input type="checkbox" name="option[]" id="option-1" value="option1" required/> Option 1
<input type="checkbox" name="option[]" id="option-2" value="option2" required/> Option 2
<input type="checkbox" name="option[]" id="option-3" value="option3" required/> Option 3
<input type="checkbox" name="option[]" id="option-4" value="option4" required/> Option 4
<input type="checkbox" name="option[]" id="option-5" value="option5" required/> Option 5
Following is jQuery script, which disables further validation check if any one is selected. Select using name element.
$cbx_group = $("input:checkbox[name='option[]']");
$cbx_group = $("input:checkbox[id^='option-']"); // name is not always helpful ;)
$cbx_group.prop('required', true);
if($cbx_group.is(":checked")){
$cbx_group.prop('required', false);
}
Small gotcha here: Since you are using html5 validation, make sure you execute this before the it gets validated i.e. before form submit.
// but this might not work as expected
$('form').submit(function(){
// code goes here
});
// So, better USE THIS INSTEAD:
$('button[type="submit"]').on('click', function() {
// skipping validation part mentioned above
});
HTML5 does not directly support requiring only one/at least one checkbox be checked in a checkbox group. Here is my solution using Javascript:
HTML
<input class='acb' type='checkbox' name='acheckbox[]' value='1' onclick='deRequire("acb")' required> One
<input class='acb' type='checkbox' name='acheckbox[]' value='2' onclick='deRequire("acb")' required> Two
JAVASCRIPT
function deRequireCb(elClass) {
el = document.getElementsByClassName(elClass);
var atLeastOneChecked = false; //at least one cb is checked
for (i = 0; i < el.length; i++) {
if (el[i].checked === true) {
atLeastOneChecked = true;
}
}
if (atLeastOneChecked === true) {
for (i = 0; i < el.length; i++) {
el[i].required = false;
}
} else {
for (i = 0; i < el.length; i++) {
el[i].required = true;
}
}
}
The javascript will ensure at least one checkbox is checked, then de-require the entire checkbox group. If the one checkbox that is checked becomes un-checked, then it will require all checkboxes, again!
I guess there's no standard HTML5 way to do this, but if you don't mind using a jQuery library, I've been able to achieve a "checkbox group" validation using webshims' "group-required" validation feature:
The docs for group-required say:
If a checkbox has the class 'group-required' at least one of the
checkboxes with the same name inside the form/document has to be
checked.
And here's an example of how you would use it:
<input name="checkbox-group" type="checkbox" class="group-required" id="checkbox-group-id" />
<input name="checkbox-group" type="checkbox" />
<input name="checkbox-group" type="checkbox" />
<input name="checkbox-group" type="checkbox" />
<input name="checkbox-group" type="checkbox" />
I mostly use webshims to polyfill HTML5 features, but it also has some great optional extensions like this one.
It even allows you to write your own custom validity rules. For example, I needed to create a checkbox group that wasn't based on the input's name, so I wrote my own validity rule for that...
we can do this easily with html5 also, just need to add some jquery code
Demo
HTML
<form>
<div class="form-group options">
<input type="checkbox" name="type[]" value="A" required /> A
<input type="checkbox" name="type[]" value="B" required /> B
<input type="checkbox" name="type[]" value="C" required /> C
<input type="submit">
</div>
</form>
Jquery
$(function(){
var requiredCheckboxes = $('.options :checkbox[required]');
requiredCheckboxes.change(function(){
if(requiredCheckboxes.is(':checked')) {
requiredCheckboxes.removeAttr('required');
} else {
requiredCheckboxes.attr('required', 'required');
}
});
});
Inspired by the answers from #thegauraw and #Brian Woodward, here's a bit I pulled together for JQuery users, including a custom validation error message:
$cbx_group = $("input:checkbox[name^='group']");
$cbx_group.on("click", function () {
if ($cbx_group.is(":checked")) {
// checkboxes become unrequired as long as one is checked
$cbx_group.prop("required", false).each(function () {
this.setCustomValidity("");
});
} else {
// require checkboxes and set custom validation error message
$cbx_group.prop("required", true).each(function () {
this.setCustomValidity("Please select at least one checkbox.");
});
}
});
Note that my form has some checkboxes checked by default.
Maybe some of you JavaScript/JQuery wizards could tighten that up even more?
I added an invisible radio to a group of checkboxes.
When at least one option is checked, the radio is also set to check.
When all options are canceled, the radio is also set to cancel.
Therefore, the form uses the radio prompt "Please check at least one option"
You can't use display: none because radio can't be focused.
I make the radio size equal to the entire checkboxes size, so it's more obvious when prompted.
HTML
<form>
<div class="checkboxs-wrapper">
<input id="radio-for-checkboxes" type="radio" name="radio-for-required-checkboxes" required/>
<input type="checkbox" name="option[]" value="option1"/>
<input type="checkbox" name="option[]" value="option2"/>
<input type="checkbox" name="option[]" value="option3"/>
</div>
<input type="submit" value="submit"/>
</form>
Javascript
var inputs = document.querySelectorAll('[name="option[]"]')
var radioForCheckboxes = document.getElementById('radio-for-checkboxes')
function checkCheckboxes () {
var isAtLeastOneServiceSelected = false;
for(var i = inputs.length-1; i >= 0; --i) {
if (inputs[i].checked) isAtLeastOneCheckboxSelected = true;
}
radioForCheckboxes.checked = isAtLeastOneCheckboxSelected
}
for(var i = inputs.length-1; i >= 0; --i) {
inputs[i].addEventListener('change', checkCheckboxes)
}
CSS
.checkboxs-wrapper {
position: relative;
}
.checkboxs-wrapper input[name="radio-for-required-checkboxes"] {
position: absolute;
margin: 0;
top: 0;
left: 0;
width: 100%;
height: 100%;
-webkit-appearance: none;
pointer-events: none;
border: none;
background: none;
}
https://jsfiddle.net/codus/q6ngpjyc/9/
I had the same problem and I my solution was this:
HTML:
<form id="processForm.php" action="post">
<div class="input check_boxes required wish_payment_type">
<div class="wish_payment_type">
<span class="checkbox payment-radio">
<label for="wish_payment_type_1">
<input class="check_boxes required" id="wish_payment_type_1" name="wish[payment_type][]" type="checkbox" value="1">Foo
</label>
</span>
<span class="checkbox payment-radio">
<label for="wish_payment_type_2">
<input class="check_boxes required" id="wish_payment_type_2" name="wish[payment_type][]" type="checkbox" value="2">Bar
</label>
</span>
<span class="checkbox payment-radio">
<label for="wish_payment_type_3">
<input class="check_boxes required" id="wish_payment_type_3" name="wish[payment_type][]" type="checkbox" value="3">Buzz
</label>
<input id='submit' type="submit" value="Submit">
</div>
</form>
JS:
var verifyPaymentType = function () {
var checkboxes = $('.wish_payment_type .checkbox');
var inputs = checkboxes.find('input');
var first = inputs.first()[0];
inputs.on('change', function () {
this.setCustomValidity('');
});
first.setCustomValidity(checkboxes.find('input:checked').length === 0 ? 'Choose one' : '');
}
$('#submit').click(verifyPaymentType);
https://jsfiddle.net/oywLo5z4/
You don't need jQuery for this. Here's a vanilla JS proof of concept using an event listener on a parent container (checkbox-group-required) of the checkboxes, the checkbox element's .checked property and Array#some.
const validate = el => {
const checkboxes = el.querySelectorAll('input[type="checkbox"]');
return [...checkboxes].some(e => e.checked);
};
const formEl = document.querySelector("form");
const statusEl = formEl.querySelector(".status-message");
const checkboxGroupEl = formEl.querySelector(".checkbox-group-required");
checkboxGroupEl.addEventListener("click", e => {
statusEl.textContent = validate(checkboxGroupEl) ? "valid" : "invalid";
});
formEl.addEventListener("submit", e => {
e.preventDefault();
if (validate(checkboxGroupEl)) {
statusEl.textContent = "Form submitted!";
// Send data from e.target to your backend
}
else {
statusEl.textContent = "Error: select at least one checkbox";
}
});
<form>
<div class="checkbox-group-required">
<input type="checkbox">
<input type="checkbox">
<input type="checkbox">
<input type="checkbox">
</div>
<input type="submit" />
<div class="status-message"></div>
</form>
If you have multiple groups to validate, add a loop over each group, optionally adding error messages or CSS to indicate which group fails validation:
const validate = el => {
const checkboxes = el.querySelectorAll('input[type="checkbox"]');
return [...checkboxes].some(e => e.checked);
};
const allValid = els => [...els].every(validate);
const formEl = document.querySelector("form");
const statusEl = formEl.querySelector(".status-message");
const checkboxGroupEls = formEl.querySelectorAll(".checkbox-group-required");
checkboxGroupEls.forEach(el =>
el.addEventListener("click", e => {
statusEl.textContent = allValid(checkboxGroupEls) ? "valid" : "invalid";
})
);
formEl.addEventListener("submit", e => {
e.preventDefault();
if (allValid(checkboxGroupEls)) {
statusEl.textContent = "Form submitted!";
}
else {
statusEl.textContent = "Error: select at least one checkbox from each group";
}
});
<form>
<div class="checkbox-group-required">
<label>
Group 1:
<input type="checkbox">
<input type="checkbox">
<input type="checkbox">
<input type="checkbox">
</label>
</div>
<div class="checkbox-group-required">
<label>
Group 2:
<input type="checkbox">
<input type="checkbox">
<input type="checkbox">
<input type="checkbox">
</label>
</div>
<input type="submit" />
<div class="status-message"></div>
</form>
I realize there are a ton of solutions here, but I found none of them hit every requirement I had:
No custom coding required
Code works on page load
No custom classes required (checkboxes or their parent)
I needed several checkbox lists to share the same name for submitting Github issues via their API, and was using the name label[] to assign labels across many form fields (two checkbox lists and a few selects and textboxes) - granted I could have achieved this without them sharing the same name, but I decided to try it, and it worked.
The only requirement for this one is jQuery, which could easily be eliminated if you wanted to rewrite it in vanilla JS. You can combine this with #ewall's great solution to add custom validation error messages.
/* required checkboxes */
jQuery(function ($) {
var $requiredCheckboxes = $("input[type='checkbox'][required]");
/* init all checkbox lists */
$requiredCheckboxes.each(function (i, el) {
//this could easily be changed to suit different parent containers
var $checkboxList = $(this).closest("div, span, p, ul, td");
if (!$checkboxList.hasClass("requiredCheckboxList"))
$checkboxList.addClass("requiredCheckboxList");
});
var $requiredCheckboxLists = $(".requiredCheckboxList");
$requiredCheckboxLists.each(function (i, el) {
var $checkboxList = $(this);
$checkboxList.on("change", "input[type='checkbox']", function (e) {
updateCheckboxesRequired($(this).parents(".requiredCheckboxList"));
});
updateCheckboxesRequired($checkboxList);
});
function updateCheckboxesRequired($checkboxList) {
var $chk = $checkboxList.find("input[type='checkbox']").eq(0),
cblName = $chk.attr("name"),
cblNameAttr = "[name='" + cblName + "']",
$checkboxes = $checkboxList.find("input[type='checkbox']" + cblNameAttr);
if ($checkboxList.find(cblNameAttr + ":checked").length > 0) {
$checkboxes.prop("required", false);
} else {
$checkboxes.prop("required", true);
}
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form method="post" action="post.php">
<div>
Type of report:
</div>
<div>
<input type="checkbox" id="chkTypeOfReportError" name="label[]" value="Error" required>
<label for="chkTypeOfReportError">Error</label>
<input type="checkbox" id="chkTypeOfReportQuestion" name="label[]" value="Question" required>
<label for="chkTypeOfReportQuestion">Question</label>
<input type="checkbox" id="chkTypeOfReportFeatureRequest" name="label[]" value="Feature Request" required>
<label for="chkTypeOfReportFeatureRequest">Feature Request</label>
</div>
<div>
Priority
</div>
<div>
<input type="checkbox" id="chkTypeOfContributionBlog" name="label[]" value="Priority: High" required>
<label for="chkPriorityHigh">High</label>
<input type="checkbox" id="chkTypeOfContributionBlog" name="label[]" value="Priority: Medium" required>
<label for="chkPriorityMedium">Medium</label>
<input type="checkbox" id="chkTypeOfContributionLow" name="label[]" value="Priority: Low" required>
<label for="chkPriorityMedium">Low</label>
</div>
<div>
<input type="submit" />
</div>
</form>
Really simple way to verify if at least one checkbox is checked:
function isAtLeastOneChecked(name) {
let checkboxes = Array.from(document.getElementsByName(name));
return checkboxes.some(e => e.checked);
}
Then you can implement whatever logic you want to display an error.
Here is another simple trick using Jquery!!
HTML
<form id="hobbieform">
<div>
<input type="checkbox" name="hobbies[]">Coding
<input type="checkbox" name="hobbies[]">Gaming
<input type="checkbox" name="hobbies[]">Driving
</div>
</form>
JQuery
$('#hobbieform').on("submit", function (e) {
var arr = $(this).serialize().toString();
if(arr.indexOf("hobbies") < 0){
e.preventDefault();
alert("You must select at least one hobbie");
}
});
That's all.. this works because if none of the checkbox is selected, nothing as regards the checkbox group(including its name) is posted to the server
Pure JS solution:
const group = document.querySelectorAll('[name="myCheckboxGroup"]');
function requireLeastOneChecked() {
var atLeastOneChecked = false;
for (i = 0; i < group.length; i++)
if (group[i].checked)
atLeastOneChecked = true;
if (atLeastOneChecked)
for (i = 0; i < group.length; i++)
group[i].required = false;
else
for (i = 0; i < group.length; i++)
group[i].required = true;
}
requireLeastOneChecked(); // onload
group.forEach(function ($el) {
$el.addEventListener('click', function () { requireLeastOneChecked(); })
});
Hi just use a text box additional to group of check box.When clicking on any check box put values in to that text box.Make that that text box required and readonly.
A general Solution without change the submit event or knowing the name of the checkboxes
Build a Function, which marks the Checkbox as HTML5-Invalid
Extend Change-Event and check validity on the start
jQuery.fn.getSiblingsCheckboxes = function () {
let $this = $(this);
let $parent = $this.closest('form, .your-checkbox-listwrapper');
return $parent.find('input[type="checkbox"][name="' + $this.attr('name')+'"]').filter('*[required], *[data-required]');
}
jQuery.fn.checkRequiredInputs = function() {
return this.each(function() {
let $this = $(this);
let $parent = $this.closest('form, .your-checkbox-list-wrapper');
let $allInputs = $this.getSiblingsCheckboxes();
if ($allInputs.filter(':checked').length > 0) {
$allInputs.each(function() {
// this.setCustomValidity(''); // not needed
$(this).removeAttr('required');
$(this).closest('li').css('color', 'green'); // for debugging only
});
} else {
$allInputs.each(function() {
// this.reportValidity(); // not needed
$(this).attr('required', 'required');
$(this).closest('li').css('color', 'red'); // for debugging only
});
}
return true;
});
};
$(document).ready(function() {
$('input[type="checkbox"][required="required"], input[type="checkbox"][required]').not('*[data-required]').not('*[disabled]').each(function() {
let $input = $(this);
let $allInputs = $input.getSiblingsCheckboxes();
$input.attr('data-required', 'required');
$input.removeAttr('required');
$input.on('change', function(event) {
$input.checkRequiredInputs();
});
});
$('input[type="checkbox"][data-required="required"]').checkRequiredInputs();
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.0.0/jquery.min.js"></script>
</head>
<form>
<ul>
<li><input type="checkbox" id="checkbox1" name="countries" value="Argentina" required="required">Argentina</li>
<li><input type="checkbox" id="checkbox2" name="countries" value="France" required="required">France</li>
<li><input type="checkbox" id="checkbox3" name="countries" value="Germany" required="required">Germany</li>
<li><input type="checkbox" id="checkbox4" name="countries" value="Japan" required="required">Japan</li>
<li><input type="checkbox" id="checkbox5" name="countries" value="Australia" required="required">Australia</li>
</ul>
<input type="submit" value="Submit">
</form>
Try:
self.request.get('sports_played', allow_multiple=True)
or
self.request.POST.getall('sports_played')
More specifically:
When you are reading data from the checkbox array, make sure array has:
len>0
In this case:
len(self.request.get('array', allow_multiple=True)) > 0

Let link deside what radio button is checked

I have 3 links on a page, when clicking on one of the links, the radio button on the other page needs to be checked.
Looks like this:
Go 1
Go 2
Go 3
I have some checkboxes on the page.html which needs to be checked.
<input type="radio" name="amount" value="1" />
<input type="radio" name="amount" value="2" />
<input type="radio" name="amount" value="3" />
When click on Go 2, checkbox 2 needs to be checked.
Anyone knows what js needs to be written?
<input type="radio" name="amount" value="1" /> 1 <br>
<input type="radio" name="amount" value="2" /> 2 <br>
<input type="radio" name="amount" value="3" /> 3 <br>
<script>
function getQueryVariable(variable) {
var query = window.location.search.substring(1);
var vars = query.split('&');
for (var i = 0; i < vars.length; i++) {
var pair = vars[i].split('=');
if (decodeURIComponent(pair[0]) == variable) {
return decodeURIComponent(pair[1]);
}
}
}
var am=getQueryVariable("amount");
var allElems = document.getElementsByName('amount');
for (i = 0; i < allElems.length; i++) {
if (allElems[i].type == 'radio' && allElems[i].value ==am ) {
allElems[i].checked = true;
}
}
</script>
Reference: getQueryVariable() function is taken from Here. Credit goes to # Dorian Gray
You'll need to get the querystring using Javascript - plenty of information on how to do that, one example:
How can I get query string values in JavaScript?
You'll then need to write some Javascript to select the radio button - again, a simple search is your friend:
javascript check radio buttons automatically
Top tip: use the search engine :)

How can I prevent a user from selecting multiple checkboxes in HTML?

How can I prevent a user from selecting multiple checkboxes in HTML?
you should change it to radio button instead of check box!
<input type="radio" name="group1" id="item1" value="Milk">
<label for="item1">Milk</label>
<br/>
<input type="radio" name="group1" id="item2" value="Butter" checked>
<label for="item2">Butter</label>
<br/>
<input type="radio" name="group1" id="item3" value="Cheese">
<label for="item13">Cheese</label>
I had a use case where I needed use checkboxes--which, unlike radio buttons, allows a user to UNcheck... Here's an example of something I pieced together from another stackoverflow user:
<head>
<meta charset=utf-8 />
<title>and-or checkboxes</title>
<script src="http://code.jquery.com/jquery-1.4.4.js"></script>
</head>
<body>
<label for="checkbox1"><input type="checkbox" id="checkbox1" name="checkbox1" value="and" </label><span id="span_and">checkbox1</span><br>
<label for="checkbox2"> <input type="checkbox" id="checkbox2" name="checkbox2" value="or" </label><span id="span_or">checkbox2</span>
<script>
$(document).ready(function(){
$('#checkbox1').click(function() {
var checkedBox = $(this).attr("checked");
if (checkedBox === true) {
$("#checkbox2").attr('checked', false);
} else {
$("#checkbox2").removeAttr('checked');
}
});
});
$(document).ready(function(){
$('#checkbox2').click(function() {
var checkedBox = $(this).attr("checked");
if (checkedBox === true) {
$("#checkbox1").attr('checked', false);
} else {
$("#checkbox1").removeAttr('checked');
}
});
});
</script>
</body>
With a little work, you can combine the either/or two scripts into a single script. You probably don't need this now but I wanted to post it because it was very useful to me.
If you want that only one checkbox get selected at a time then its better to use radiobutton instead.
If you mean that you don't want multiple checkboxes from a same "logical group" to be checked at one time, you should use radio buttons instead of checkboxes.
<form>
<input type="radio" name="aGroup" value="choice1" /> Choice #1<br />
<input type="radio" name="aGroup" value="choice2" /> Choice #2
</form>
By using this, only 1 option can be checked at one time
Use Radio, and they must have the same name="".