Develop Reference

Reveal additional info based on two (out of three) checkboxes JavaScript

I'm new at Javascript and I'm trying to reveal additional info only if any 2 out of 3 checkboxes are checked.
Here is my code so far (I'm trying to enter my code in the question but It's not working, sorry. I also may have made it more complicated then necessary, sorry again). I did place my code in the Demo.
<script>
var checkboxes;
window.addEvent('domready', function() {
var i, checkbox, textarea, div, textbox;
checkboxes = {};
// link the checkboxes and textarea ids here
checkboxes['checkbox_1'] = 'textarea_1';
checkboxes['checkbox_2'] = 'textarea_2';
checkboxes['checkbox_3'] = 'textarea_3';
for ( i in checkboxes ) {
checkbox = $(i);
textbox = $(checkboxes[i]);
div = $(textbox.id + '_container_div');
div.dissolve();
showHide(i);
addEventToCheckbox(checkbox);
}
function addEventToCheckbox(checkbox) {
checkbox.addEvent('click', function(event) {
showHide(event.target.id);
});
}
});
function showHide(id) {
var checkbox, textarea, div;
if(typeof id == 'undefined') {
return;
}
checkbox = $(id);
textarea = checkboxes[id];
div = $(textarea + '_container_div');
textarea = $(textarea);
if(checkbox.checked) {
div.setStyle('display', 'block');
//div.reveal();
div.setStyle('display', 'block');
textarea.disabled = false;
} else {
div.setStyle('display', 'none');
//div.dissolve();
textarea.value = '';
textarea.disabled = true;
}
}
<label for="choice-positive">
<script type="text/javascript">
function validate(f){
f = f.elements;
for (var c = 0, i = f.length - 1; i > -1; --i)
if (f[i].name && /^colors\[\d+\]$/.test(f[i].name) && f[i].checked) ++c;
return c <= 1;
};
</script>
<label>
<h4><div style="text-align: left"><font color="black">
<input type="checkbox" name="colors[2]" value="address" id="address">Full Address
<br>
<label>
<input type="checkbox" name="colors[3]" value="phone" id="phone">Phone Number <br>
<label>
<input type="checkbox" name="colors[4]" value="account" id="account">Account Number <br>
</form>
<div class="reveal-if-active">
<h2><p style = "text-decoration:underline;"><font color="green">Receive the 2 following
pieces of info:</h2></p>
</style>

Sorry i wasn't able to exactly use the code you provided but tried to change just enough to get it working.
I've uploaded a possible solution to JSFiddle - you essentially can add event listeners to the checkboxes that recheck when clicked how many are selected and show/hide via removing/adding a class e.g. additionalContactBox.classList.remove('reveal-if-active');

check if user inserted value higher then 0 with vanilla js

I am creating a custom js validator from scratch, without the use of any libraries.
I want to validate a numeric input by checking if the user-inserted content in the input tag is great than 0:
<label>Price
<input type="text" id="price" name="price">
</label>
Attempt:
function price()
{
if (#price.value>0)
console.log('0.');
else
console.log('Incorrect');
}

Would this not work:
if(price.value.match(/^[0-9]+$/) && +(price.value) > 0){
im not quite sure what the hash symbol is being used for so i removed it in my example. Unless you are trying to find the ID in which you would have to look for the element like so:
var price = document.querySelector("#price");

function price()
{
var price = document.getElementById("#price"); // get the element
if (isNaN(price.value) || price.value <= 0) // if the value is not a number or is less than 0
console.log('Incorect');
else // otherwise
console.log('Correct');
}

How about some thing like that
var price = document.getElementById("price").value;
if (parseInt(price) > 0 && !isNaN(price)))
{
// then do something
}
else
{
// else do something
}

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!!

How to hide the parent of an unchecked checkbox?

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!

Comparing two input fields

I have this function which i am using to compare two input fields. If the user enters the same number in both the text field. On submit there will be an error. Now i would like to know if there is a way to allow same number but not higher than or lower the value of the previous text box by 1. For example if user enters 5 in previous text box, the user can only input either 4, 5 or 6 in the other input field.Please give me some suggestions.
<script type="text/javascript">
function Validate(objForm) {
var arrNames=new Array("text1", "text2");
var arrValues=new Array();
for (var i=0; i<arrNames.length; i++) {
var curValue = objForm.elements[arrNames[i]].value;
if (arrValues[curValue + 2]) {
alert("can't have duplicate!");
return false;
}
arrValues[curValue] = arrNames[i];
}
return true;
}
</script>
<form onsubmit="return Validate(this);">
<input type="text" name="text1" /><input type="text" name="text2" /><button type="submit">Submit</button>
</form>

A tidy way to do it which is easy to read:
var firstInput = document.getElementById("first").value;
var secondInput = document.getElementById("second").value;
if (firstInput === secondInput) {
// do something here if inputs are same
} else if (firstInput > secondInput) {
// do something if the first input is greater than the second
} else {
// do something if the first input is less than the second
}
This allows you to use the values again after comparison as variables (firstInput), (secondInput).

Here's a suggestion/hint
if (Math.abs(v1 - v2) <= 1) {
alert("can't have duplicate!");
return false;
}
And here's the jsfiddle link, if you want to see the answer

Give them both IDs.
Then use the
if(document.getElementById("first").value == document.getElementById("second").value){
//they are the same, do stuff for the same
}else if(document.getElementById("first").value >= document.getElementById("second").value
//first is more than second
}
and so on.