I want a checkbox to be updated when a value changes. In this short example, if the second checkbox is checked, then the first should be update and checked, too. The functionality of the first checkbox should still stay intact. How can I achieve this?
function onoff() {
currentvalue = document.getElementById('onoff').value;
if (currentvalue == "Off") {
document.getElementById("onoff").value = "On";
console.debug("OFF");
} else {
document.getElementById("onoff").value = "Off";
console.debug("ON");
}
}
function xy() {
document.getElementById('onoff').value = "On";
console.debug("xy");
}
<input type="checkbox" value="On" id="onoff" onclick="onoff();">
<input type="checkbox" value="Off" id="xy" onclick="xy();">
Related
I got a problem switching a button both ways, by clicking on it and by changing it by a js-function which reacts on recieved mqtt messages and toggles the button. The first part works, the latter not. Here is my html
<label class="switch">
<input type="checkbox" value="On" id="onoff" onclick="onoff_dev();">
<span class="slider round"></span>
</label>
The js to toggle the button:
function onoff_dev() {
currentvalue = document.getElementById('onoff').value;
if (currentvalue == "Off") {
document.getElementById("onoff").value = "On";
switch("0");
} else {
document.getElementById("onoff").value = "Off";
switch("1");
}
}
And here the function, which is executed when a mqtt message arrives. The message is either 'r_message = On' or 'r_message = Off' It should change the slide button, but "document.getElementById('onoff').value = "On";" does not update the value of the button.
function onMessageArrived(r_message) {
if (r_message == "On") {
document.getElementById('onoff').value = "On";
}
if (r_message == "Off") {
document.getElementById('onoff').value = "Off";
}
}
Can you please help me? Thanks!
I have a code in which if my checkbox is checked and if I load window(page) checkbox should remain there on reload OR if I uncheck the checkbox and reload page then checkbox should remain unchecked. my code is as following.
<input type="checkbox" id="chk">
<script>
window.onload = onPageLoad();
function onPageLoad() {
if (document.getElementById("chk").checked == true) {
document.getElementById("chk").checked = true;
} else {
document.getElementById("chk").checked = false;
}
}
</script>
However above code returns unchecked checkbox even after reloading page after checking checkbox.
Just add "checked" attribute to HTML tag:
<input type="checkbox" checked>
But if you need to keep checked input after page reload you need to add a storage info. Maybe help:
<input type="checkbox" id="chk">
<script>
window.addEventListener('load', function() {
document.querySelector("#chk").addEventListener('change', function(el) {
console.log(el.target.checked);
localStorage.setItem('input_checked', el.target.checked );
});
if ( localStorage.getItem('input_checked') !== null ) {
document.querySelector('#chk').checked = localStorage.getItem('input_checked') === 'true';
}
});
</script>
Is this the proper way to use a checkbox in JS. I can only get the event to fire one time, not each time I click the box.
var checkbox = document.checkbox;
checkbox.addEventListener('change', function(){
switch(this.value){
case "on":
checkbox.value = "off"; break;
case "off":
checkbox.value = "on"; break;
}
<input type="checkbox" name = "checkbox" checked = "checked" value = "on">
You don't want spaces around your equals sign in HTML. Also, a switch statement is a little verbose for when you have less than three conditions.
Not sure what you are trying to accomplish exactly, but here you go.
var checkbox = document.querySelector('.checkbox');
checkbox.addEventListener('change', function(){
this.checked ? this.setAttribute('value', 'on') : this.setAttribute('value', 'off');
});
<input class="checkbox" type="checkbox" name="checkbox" />
Make sure to get a reference to the checkbox using the proper API:
// Get a reference to the element the proper way:
var checkbox = document.querySelector("input[type='checkbox']");
checkbox.addEventListener('change', function(){
switch(this.value){
case "on":
this.value = "off";
break;
case "off":
this.value = "on";
break;
}
console.log(this.value)
});
<input type="checkbox" name = "checkbox" checked = "checked" value = "on">
With that said, it's not super useful to change the value of a checkbox because it's checked. The usual way a checkbox is used is either to submit its value as part of a form submission or to use as a Boolean indicator of some state for "in-page" behavior. You generally don't want or need to change the value of a checkbox, instead you simply want to know if it is checked, which can be done by looking at its .checked property and making decisions based on that. A checkbox will have a checked property value of true when it's been checked and false when it isn't.
// Get a reference to the element the proper way:
var checkbox = document.querySelector("input[type='checkbox']");
checkbox.addEventListener('change', function(){
if(this.checked){
console.log("Checkbox is checked! Do something about it!");
} else {
console.log("Forget it. Checkbox wasn't checked.");
}
});
<input type="checkbox" name = "checkbox" value = "on">
No need of JS for this:
#chkBx + label { display:none; }
#chkBx:checked + label { display:inline; }
#chkBx:checked + label + label { display:none; }
<input type="checkbox" id="chkBx" checked ><label for="chkBx">On</label><label for="chkBx">Off</label>
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 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...