Hallo
How would I go about in checking whether checkBox has been checked in javascript?
I C# it is simple enough
int selected = 0;
for (int loop = 0; loop < chkMeal.CheckedItems.Count; loop++)
{
selected++;
}
if (selected > 1)
{
MessageBox.Show("only one meal allowed", "Halt", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
How could I do a simlar thing with javascript?
kind regards
Arian
For instance, if you give your checkboxes a class you can do something like this:
var myboxes = document.getElementsByClassName('myboxes');
for (var i=0; i<myboxes.length;i++) {
if (myboxes[i].checked) {
alert('Box number '+i+' is checked!');
}
}
Simply put, give your form a unique id attribute. Then, traverse HTMLFormElement.elements and check against HTMLInputElement.checked for a truthy value.
HTML:
<form id="foo" method="post" action="./">
<input type="checkbox" name="check_a" value="foo" />
<input type="checkbox" name="check_b" value="bar" />
<input type="checkbox" name="check_c" value="baz" checked />
</form>
JS:
var foo = document.getElementById("foo"), i = 0, el;
for(i;i<foo.elements.length;i++)
{
el = foo.elements[i];
if(el.nodeType === 1 && el.tagName === "INPUT" && el.type === "checkbox")
{
//element node, is an input element, is a checkbox
if(el.checked)
{
//checkbox is checked
}
}
el = null;
}
Bonus reference:
HTMLFormElement (via DOM Level 2)
HTMLInputElement (via DOM Level 2)
Using a little bit of jQuery:
$(function() {
$('form').submit( function() {
if ($('[name="chkMeal"]:checked').length > 1) {
// show an error
return false; // cancel submit
}
});
});
Related
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!!
I have an HTML form with checkboxes like so:
<form id="filterOptions" method="post" action="">
<input type="checkbox" name="filterTaxi" id="filterTaxi" />
<input type="checkbox" name="filterBicycle" id="filterBicycle" />
<input type="checkbox" name="filterCarPark" id="filterCarPark" />
<input type="checkbox" name="filterBed" id="filterBed" />
</form>
Now I want to use javascript to apply a function whenever a checkbox is changed.
At the moment I can apply a function when the first checkbox is changed like so:
document.getElementById('filterTaxi').onchange = function(){
//do something here
};
So my question is, how do I avoid writing that for every checkbox and instead have a function fired when any of the checkboxes are changed?
You can either select all input or add a class and do:
var input = document.getElementsByTagName('input');
for(var i = 0; i < input.length; i++) {
input[i].onchange = function() {
console.log(this);
}
}
onchange function can be the same for all of them.
fiddle: http://jsfiddle.net/XgS9K/
for all elements.
document.getElementById('filterOptions').onchange = function(){
alert()
};
This will give you the onchange handler for checking and unchecking of checkboxes.
var allInputs = document.getElementsByTagName('input');
for (var i = 0; i < allInputs.length; i++) {
if (allInputs[i].type == 'checkbox') {
allInputs[i].onchange = function () {
if (this.checked) {
// your checked code here
console.log('checked');
} else {
// your unchecked code here
console.log('unchecked');
}
}
}
}
DEMO http://jsfiddle.net/L324t/
I have a set of random/dynamic generated div checkboxes:
<div>A1 <input type='checkbox' name='A[]' value='A1'> </div>
<div>A2 <input type='checkbox' name='A[]' value='A2'> </div>
<div>A3 <input type='checkbox' name='A[]' value='A3'> </div>
<div>B1 <input type='checkbox' name='B[]' value='B1'> </div>
<div>B2 <input type='checkbox' name='B[]' value='B2'> </div>
<div>C1 <input type='checkbox' name='C[]' value='C1'> </div>
What I am trying to do is when the user:
checks any A then the others will hide (entire div) but all A will still show.
unchecks a checkbox, then all A, B, C will show again.
This is because I am preventing the user from checking a mix of options.
PS:
You can provide a solution that might need me to modify the generated output of checkboxes.
try this fiddle
$("input[type=checkbox]").on("change", function() {
var thisName = $(this).attr("name");
if($(this).is(':checked')){
$(':checkbox').parent().hide();
$('input:checkbox[name|="'+thisName+'"]').parent().show();
} else {
$(':checkbox').parent().show();
}
});
Try this one,
$('input:checkbox').click(function(){
if($(this).attr('checked') == 'checked'){
$('input:checkbox').parent('div').hide();
$('input:checkbox[name="'+$(this).attr('name')+'"]').parent('div').show();
}else{
if(!$('input:checkbox[checked="checked"]').length){
$('input:checkbox').parent('div').show();
}
}
})
Demo: http://jsfiddle.net/muthkum/uRd3e/3/
You can use some JQuery traversing to hide the non-matching elements:
// add the event handler
$("input[type=checkbox]").on("change", function() {
// get whether checked or unchecked
var checked = $(this).prop("checked") === true;
// get the name of the clicked element (eg, "A[]")
var thisName = $(this).prop("name");
// get the name of the clicked element (eg, "A[]")
var thisName = $(this).prop("name");
// get the grandparent element
$(this).parent().parent()
// get all the checkboxes
.find("input[type=checkbox]")
// filter to only the ones that don't match the current name
.filter(function(i, e) { return e.name != thisName; })
// hide or display them
.css("display", checked ? "none" : "");
});
you can simple do it like this
$('input[type=checkbox]').change(function () {
if ($(this).attr('checked')) {
var Name = $(this).prop("name");
$('div').filter(function(){
return $(this).find('input[type=checkbox]').prop("name") != Name;
}).hide();
}
else
{
$('input[type=checkbox]').attr('checked',false);
$('input[type=checkbox]').parent('div').show();
}
});
Live Demo
Try code bellow:
$(":checkbox").click(function() {
var identifier = $(this).val().substring(0, 1);
$("input[type='checkbox']").each(function() {
if ($(this).val().indexOf(identifier) != -1) {
$(this).parent().show();
} else {
$(this).parent().hide();
}
});
if ($("input:checked").length == 0) {
$("input[type='checkbox']").parent().show();
}
});
You can try on jsFiddle
This will hide all other checkbox types when FIRST of a type is checked and show all the other checkbox types when ALL of the checked box type are unchecked:
$("input:checkbox").on("change", function() {
// get the name attribute
var nameAttr = $(this).prop("name");
// check how many checkbox inputs of that name attribute are checked
var checkedLength = $("input:checkbox[name=\"" + nameAttr + "\"]:checked").length;
// if 0, display other checkbox inputs, else if 1 hide all of the rest
if(checkedLength == 0) {
$("input:checkbox[name!=\"" + nameAttr + "\"]").parent().show();
}else if(checkedLength == 1) {
$("input:checkbox[name!=\"" + nameAttr + "\"]").parent().hide();
}
});
Overwhelmed by choice! Here's a plain JS version that just disables members of the non–selected groups.
I think that's better than hiding them so users can see the other options after they've selected one. Otherwise, to see the other options again, they must deselect all checkboxes in the group.
Note that div is a parent of the inputs, the listener passes a reference to the element and the related event object, modify as required.
<script>
function doStuff(div, evt) {
var checked, el, group, j, inputs, name, re;
var t = evt.target || evt.srcElement;
if (t.nodeName && t.nodeName.toLowerCase() == 'input' && t.type == 'checkbox') {
inputs = div.getElementsByTagName('input');
name = t.name;
// Set checked to true if any input with this name is checked
group = document.getElementsByName(name);
j = group.length;
while (j-- && !checked) {
checked = group[j].checked;
}
// Loop over inputs, hide or show depending on tests
for (var i=0, iLen=inputs.length; i<iLen; i++) {
el = inputs[i];
// If name doesn't match, disable
el.disabled = checked? (el.name != name) : false;
}
}
}
</script>
<div onclick="doStuff(this, event)">
<div>A1 <input type='checkbox' name='A[]' value='A1'></div>
<div>A2 <input type='checkbox' name='A[]' value='A2'></div>
<div>A3 <input type='checkbox' name='A[]' value='A3'></div>
<div>B1 <input type='checkbox' name='B[]' value='B1'></div>
<div>B2 <input type='checkbox' name='B[]' value='B2'></div>
<div>C1 <input type='checkbox' name='C[]' value='C1'></div>
</div>
Thanks guys, especially dbaseman (get me ideal) :
ok, Here is my code after referring from you all.
$("input[type=checkbox]").on("click", function() {
var sta = $(this).is(":checked"); sta=(sta==true?1:0);
if(sta==1){
var thisName = $(this).prop("name"); thisName=thisName.replace("[]","");
$("div input[type=checkbox]:not([name^=" + thisName + "])").parent().hide();
}else{
var num = $("[type=checkbox]:checked").length;
if(num==0){
$("div input[type=checkbox]").parent().show();
}
}
});
so far code able is performing as what i need.
Ps: i am still weak on jquery travelling part
Ps: Edited on re-opening all checkboxes part
Thanks once again!
here am trying to display divs ClinicFieldSet and HospitalFieldset by selecting the given text boxes. If both are selected, both ClinicFieldset and HospitalFieldset should display and if one of the check box is selected it should show which div is selected.
The problem with my script is, when one of the checkboxes are clicked, both checkboxes are getting selected and it is not posible to uncheck them also. So please suggest me an idea to fix this problem :(
I used Javascript onClick in both checkboxes to apply on both of them.
<script type="text/javascript>
var clinic = document.getElementById('clinic');
var visit = document.getElementById('visit');
if((clinic.checked = true) && (visit.checked = true) )
{
document.getElementById('ClinicFieldSet').style.display='block';
document.getElementById('HospitalFieldSet').style.display='block';
}
else if((clinic.checked = true) && (visit.checked = false))
{
document.getElementById('ClinicFieldSet').style.display='block';
document.getElementById('HospitalFieldSet').style.display='none';
}
else if((clinic.checked = false) && (visit.checked = true))
{
document.getElementById('ClinicFieldSet').style.display='none';
document.getElementById('HospitalFieldSet').style.display='block';
}
else
{
document.getElementById('ClinicFieldSet').style.display='none';
document.getElementById('HospitalFieldSet').style.display='none';
}
HTML
<input type="checkbox" name="type" id="clinic" onClick="dispp();" >Clinic Practice
<input type="checkbox" name="type" id="visit" onClick="dispp();" >Visiting Hospital
In your if statement use the == equality operator.
The single = is used to assign a value, not test its equality.
May I suggest a revised approach (not using in-line click-handlers) with a slightly amended html, just to make the JavaScript somewhat more simple:
HTML:
<input type="checkbox" name="type" id="clinic" /><label for="clinic">Clinic Practice</label>
<input type="checkbox" name="type" id="hospital" /><label for="hospital">Visiting Hospital</label>
<div id="clinicInfo">
<h2>Clinic information</h2>
</div>
<div id="hospitalInfo">
<h2>Hospital information</h2>
</div>
JavaScript:
document.getElementById('hospitalInfo').style.display = 'none';
document.getElementById('clinicInfo').style.display = 'none';
var inputs = document.getElementsByTagName('input');
function dispp() {
if (this.checked) {
document.getElementById(this.id + 'Info').style.display = 'block';
}
else {
document.getElementById(this.id + 'Info').style.display = 'none';
}
}
for (i = 0; i < inputs.length; i++) {
if (inputs[i].type.toLowerCase() == 'checkbox') {
inputs[i].onchange = dispp;
}
}
JS Fiddle demo.
Try this
if(clinic.checked == true)
{
document.getElementById('ClinicFieldSet').style.display='block';
}
else
{
document.getElementById('ClinicFieldSet').style.display='none';
}
if(visit.checked == true)
{
document.getElementById('HospitalFieldSet').style.display='block';
}
else
{
document.getElementById('HospitalFieldSet').style.display='none';
}
var form=document.forms.add
form.elements.check.addEventListener('change',function(e) {
e.preventDefault()
var check=document.querySelector('.check')
if(check.checked=true)
{
document.querySelector('.inside').style.display='block'
}
else{
document.querySelector('.inside').style.display='none'
}
})
I am implementing an HTML form with some checkbox input elements, and I want to have a Select All or DeSelect All button. However, I do not want to rely on the name of the input element (like this example) but rather the type because I have multiple checkbox groups with different names. Is there a way to check and uncheck all checkbox input elements within a form with JavaScript by relying on the type instead of the name?
Edit: We rely on YUI libraries, so I have access YUI if that provides a solution.
This should do it:
<script>
function checkUncheck(form, setTo) {
var c = document.getElementById(form).getElementsByTagName('input');
for (var i = 0; i < c.length; i++) {
if (c[i].type == 'checkbox') {
c[i].checked = setTo;
}
}
}
</script>
<form id='myForm'>
<input type='checkbox' name='test' value='1'><br>
<input type='checkbox' name='test' value='1'><br>
<input type='checkbox' name='test' value='1'><br>
<input type='checkbox' name='test' value='1'><br>
<input type='checkbox' name='test' value='1'><br>
<input type='button' onclick="checkUncheck('myForm', true);" value='Check'>
<input type='button' onclick="checkUncheck('myForm', false);" value='Uncheck'>
</form>
function findCheckBoxes(el, check) {
for(var i=0;el.childNodes[i];i++)
{
var child = el.childNodes[i];
if (child.type=="checkbox")
{
child.checked = check;
}
if (child.childNodes.length > 0)
this.findCheckBoxes(child, check);
}
}
iterate through the form.elements collection and check .type == "checkbox".
var button = getSelectAllButtonInFormSomeHow();
/*all formelements have a reference to the form. And the form has an elements-collection.*/
var elements = button.form.elements;
for(var i = 0; i < elements.length;i++) {
var input = elements[i];
if (input.tagName == "input" && input.type == "checkbox") input.checked = true;
}
Every input element has an attribute, type, which for checkboxes is "checkbox" so you could try something like this:
for (var i = 0; i < document.myForm.elements.length; i++) {
if (document.myForm.elements[i].type == "checkbox") {
document.myForm.elements[i].checked = true;
}
}
If jQuery is an option you can do this rather easily.
See the documentation on jQuery selectors. (The last example in the section shows how to do it with radio buttons but just replace that with check boxes.)
Is assigning a class to all required checkbox elements an option? If yes, then this is how I would do it (assuming "class_name" is the name of the css class present in all checkbox elements in question):
function selectCheckBoxes(bChecked) {
var aCheckBoxes = YAHOO.util.Dom.getElementsByClassName('class_name', 'input');
for (var i = 0; i < aCheckBoxes.length; i++) {
aCheckBoxes[i].checked = bChecked;
}
}
If you want to stay away from classes, but can get parent element by ID (or any other method, I will use ID in the example, though), than you can do this:
function selectCheckBoxes(bChecked) {
var oParent = document.getElementById('parentsID');
var aElements = oParent.getElementsByTagName('input');
for (var i = 0; i < aElements.length; i++) {
if (aElements[i].type == 'checkbox') {
aElements[i].checked = bChecked;
}
}
}
I would stick to the "class" method, however.
<html>
<head>
<script>
function selectCheckBox()
{
if(document.getElementById('id11').checked==true)
{
document.frm.id2.checked=true
document.frm.id3.checked=true
document.frm.id4.checked=true
}
if(document.getElementById('id11').checked==false)
{
document.frm.id2.checked=false
document.frm.id3.checked=false
document.frm.id4.checked=false
}
}
function selectCheckBox1()
{
if(document.getElementById('id12').checked==false)
{
document.frm.id1.checked=false
}
}
function selectCheckBox2()
{
if(document.getElementById('id13').checked==false)
{
document.frm.id1.checked=false
}
}
function selectCheckBox3()
{
if(document.getElementById('id14').checked==false)
{
document.frm.id1.checked=false
}
}
</script>
</head>
<body>
<form name="frm">
All :<input type="checkbox" id="id11" name="id1" value="1" onClick="selectCheckBox()"><br>
A. :<input type="checkbox" id="id12" name="id2" value="2" onClick="selectCheckBox1()"><br>
B. :<input type="checkbox" id="id13" name="id3" value="3" onClick="selectCheckBox2()"><br>
C. :<input type="checkbox" id="id14" name="id4" value="4" onClick="selectCheckBox3()"><br>
</form>
</body>
</html>