How to validate a form with multiple checkboxes to have atleast one checked

Question

I m trying to validate a form using the validate plugin for jquery   I want to require that  the user check at least one checkbox in a group in order for the form to be submitted   Here s my jquery code       ready function         subscribeForm   validate      rules      list   required    list0 checked         messages     list    Please select at least one newsletter                                                                       and here s the html form    lt form action    method  GET  id  subscribeForm  gt   lt fieldset id  cbgroup  gt       lt div gt  lt input name  list  id  list0  type  checkbox   value  newsletter0   gt zero lt  div gt       lt div gt  lt input name  list  id  list1  type  checkbox   value  newsletter1   gt one lt  div gt       lt div gt  lt input name  list  id  list2  type  checkbox   value  newsletter2   gt two lt  div gt   lt  fieldset gt   lt input name  submit  type  submit   value  submit  gt      The problem is that the form submits even if nothing is checked   How can I resolve this

User · Accepted Answer

This script below should put you on the right track perhaps?

You can keep this html the same (though I changed the method to POST):

<form method="POST" id="subscribeForm">
    <fieldset id="cbgroup">
        <div><input name="list" id="list0" type="checkbox"  value="newsletter0" >zero</div>
        <div><input name="list" id="list1" type="checkbox"  value="newsletter1" >one</div>
        <div><input name="list" id="list2" type="checkbox"  value="newsletter2" >two</div>
    </fieldset>
    <input name="submit" type="submit"  value="submit">
</form>

and this javascript validates

function onSubmit() 
{ 
    var fields = $("input[name='list']").serializeArray(); 
    if (fields.length === 0) 
    { 
        alert('nothing selected'); 
        // cancel submit
        return false;
    } 
    else 
    { 
        alert(fields.length + " items selected"); 
    }
}

// register event on form, not submit button
$('#subscribeForm').submit(onSubmit)

and you can find a working example of it here

UPDATE (Oct 2012)
Additionally it should be noted that the checkboxes must have a "name" property, or else they will not be added to the array. Only having "id" will not work.

UPDATE (May 2013)
Moved the submit registration to javascript and registered the submit onto the form (as it should have been originally)

UPDATE (June 2016)
Changes == to ===

User · Answer

How about this     validate addMethod cb selectone                     function value element                              if element length gt 0                                  for var i 0 i lt element length i                                     if   element i   val  checked    return true                                                              return false                                                           return false                                          Please select a least one     Now you ca do     validate  rules  checklist  cb selectone        You can even go further a specify the minimum number to select with a third param in the callback function I have not tested it yet so tell me if it works

User · Answer

subscribeForm   validate          rules              list                  required  true                minlength  1                               I think this will make sure at least one is checked

User · Answer

I had to do the same thing and this is what I wrote I made it more flexible in my case as I had multiple group of check boxes to check      param  reqNum number of checkboxes to select   fn checkboxValidate   function reqNum       var fields   this serializeArray        return  fields length  lt  reqNum     invalid     valid       then you can pass this function to check multiple group of checkboxes with multiple rules      helper function to create error function err msg       alert  Please select a     msg     preference            reg   submit function e         needs at lease 2 checkboxes to be selected     if    input region  input music   checkboxValidate 2      invalid            err  Region and Music

User · Answer

if     document forms  form    mon   checked  false  amp  amp    document forms  form    tues   checked  false  amp  amp    document forms  form    wed   checked  false  amp  amp    document forms  form    thrs   checked  false  amp  amp    document forms  form    fri   checked  false       alert  Select at least One Day into Five Days      return false

User · Answer

Good example without custom validate methods  but with metadata plugin and some extra html   Demo from Jquery Validate plugin author

User · Answer

I had a slighlty different scenario  My checkboxes were created in dynamic and they were not of same group  But atleast any one of them had to be checked  My approach  never say this is perfect   I created a genric validator for all of them   jQuery validator addMethod  validatorName   function value  element        if      input checkbox name chkBox1  checked   val       Val1                  input checkbox name chkBox2  checked   val       Val2                  input checkbox name chkBox3  checked   val       Val3                      return true            else               return false                   Please Select any one value      Now I had to associate each of the chkbox to this one single validator   Again I had to trigger the validation when any of the checkboxes were clicked triggering the validator       piRequest input checkbox name chkBox1    click function e           myform   valid

User · Answer

Here is the a quick solution for multiple checkbox validation using jquery validation plugin   jQuery validator addMethod  atLeastOneChecked   function value  element      return      cbgroup input checked   length  gt  0            subscribeForm   validate     rules        list0    atLeastOneChecked  true          messages        list0     Please check at least one option                 cbgroup input   click function           list0   valid

User · Answer

How about this     document  ready function             subscribeForm   submit function             var  fields     this  find  input name  list   checked            if    fields length                alert  You must check at least one box                 return false     The form will  not  submit

User · Answer

The above addMethod by Lod Lawson is not completely correct  It s   validator and not   validate and the validator method name cb selectone requires quotes  Here is a corrected version that I tested     validator addMethod  cb selectone   function value element       if element length gt 0           for var i 0 i lt element length i                 if   element i   val  checked    return true                    return false            return false      Please select at least one option

User · Answer

I checked all answers and even in other similar questions  I tried to find optimal way with help of html class and custom rule   my html structure for multiple checkboxes are like this   x000D   x000D    validator addMethod  multicheckbox rule   function  value  element    x000D     var  parent     element  closest   checkbox wrapper    x000D     if  parent find   checkbox item   is   checked    return true  x000D              return false  x000D      Please at least select one    x000D   lt div class  checkbox wrapper  gt  x000D   lt label for  checkbox-1  gt  lt input class  checkbox item  id  checkbox-1   name  checkbox item 1   type  checkbox  value  1  data-rule-multicheckbox rule  1    gt  Checkbox item 1 lt  label gt  x000D   lt label for  checkbox-2  gt  lt input class  checkbox item  id  checkbox-2  name  checkbox item 2   type  checkbox  value  1  data-rule-multicheckbox rule  1    gt  Checkbox item 1 lt  label gt  x000D   lt  div gt  x000D   x000D   x000D

[javascript] How to validate a form with multiple checkboxes to have atleast one checked

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