Simple JavaScript Checkbox Validation

Question

I usually work with PHP so sadly don't have some basic JS principles down. This is all I want to accomplish--I've seen many posts on this topic but they are usually beyond what I need.

Here is my form:

 <input type="checkbox" name="checkbox" value="check"  />
 <input type="submit" name="email_submit" value="submit" onclick="----??----"  />

The checkbox is a simple "I agree". I want the submit button to be pressed and it will only submit if that check box is selected.

Here's the thing: I want the simple, cheating way -- no methods -- just some inline code in that form (assuming its not overly long?). This is not a public page, I just need something quick and simple with that type of validation. If its unchecked, it will throw an alert(); if its checked it will submit via post through php and go on as normal.

Answer 1

You could use:

 if(!this.form.checkbox.checked)
{
    alert('You must agree to the terms first.');
    return false;
}

( demo page ).

<input type="checkbox" name="checkbox" value="check"  />
<input type="submit" name="email_submit" value="submit" onclick="if(!this.form.checkbox.checked){alert('You must agree to the terms first.');return false}"  />

• Returning false from an inline event handler will prevent the default action from taking place (in this case, submitting the form).
• ! is the Boolean NOT operator .
• this is the submit button because it is the element the event handler is attached to.
• .form is the form the submit button is in.
• .checkbox is the control named "checkbox" in that form.
• .checked is true if the checkbox is checked and false if the checkbox is unchecked.

Answer 2

For now no jquery or php needed. Use just "required" HTML5 input attrbute like here

 <form>
        <p>
            <input class="form-control" type="text" name="email" />
            <input type="submit" value="ok" class="btn btn-success" name="submit" />
            <input type="hidden" name="action" value="0" />
        </p>
        <p><input type="checkbox" required name="terms">I have read and accept <a href="#">SOMETHING Terms and Conditions</a></p>
 </form>

This will validate and prevent any submit before checkbox is opt in. Language independent solution because its generated by users web browser.

Answer 3

You can do something like this:

<form action="../" onsubmit="return checkCheckBoxes(this);">
    <p><input type="CHECKBOX" name="MyCheckbox" value="This..."> This...</p>
    <p><input type="SUBMIT" value="Submit!"></p>
</form>

<script type="text/javascript" language="JavaScript">
<!--
function checkCheckBoxes(theForm) {
    if (
    theForm.MyCheckbox.checked == false) 
    {
        alert ('You didn\'t choose any of the checkboxes!');
        return false;
    } else {    
        return true;
    }
}
//-->
</script> 

http://lab.artlung.com/validate-checkbox/

Although less legible imho, this can be done without a separate function definition like this:

<form action="../" onsubmit="if (this.MyCheckbox.checked == false) { alert ('You didn\'t choose any of the checkboxes!'); return false; } else { return true; }">
    <p><input type="CHECKBOX" name="MyCheckbox" value="This..."> This...</p>
    <p><input type="SUBMIT" value="Submit!"></p>
</form>

Answer 4

You can do the following:

<form action="/" onsubmit="if(document.getElementById('agree').checked) { return true; } else { alert('please agree'); return false; }">
    <input type="checkbox" name="checkbox" value="check" id="agree" />
    <input type="submit" name="email_submit" value="submit" />
</form>​

Here is a working demo - http://jsfiddle.net/Ccr2x/

Answer 5

If your checkbox has an ID of 'checkbox':

 if(document.getElementById('checkbox').checked == true){ // code here }

HTH

Answer 6

var confirm=document.getElementById("confirm").value;
         if((confirm.checked==false)
         {
         alert("plz check the checkbox field");
         document.getElementbyId("confirm").focus();
         return false;
         }

Answer 7

If the check box's ID " Delete " then for the " onclick " event of the submit button the javascript function can be as follows:

html:
<input type="checkbox" name="Delete" value="Delete" id="Delete"></td>
<input type="button" value="Delete" name="delBtn" id="delBtn" onclick="deleteData()">

script:
<script type="text/Javascript">
    function deleteData() {
        if(!document.getElementById('Delete').checked){
            alert('Checkbox not checked');
            return false;
        }
</script>

Answer 8

Another simple way is to create a function and check if the checkbox(es) are checked or not, and disable a button that way using jQuery.

HTML:

<input type="checkbox" id="myCheckbox" />
<input type="submit" id="myButton" />

JavaScript:

var alterDisabledState = function () {

var isMyCheckboxChecked = $('#myCheckbox').is(':checked');

     if (isMyCheckboxChecked) {
     $('myButton').removeAttr("disabled");
     } 
     else {
             $('myButton').attr("disabled", "disabled");
     }
}

Now you have a button that is disabled until they select the checkbox, and now you have a better user experience. I would make sure that you still do the server side validation though.

Answer 9

Another Simple way is to create & invoke the function validate() when the form loads & when submit button is clicked. By using checked property we check whether the checkbox is selected or not. cbox[0] has an index 0 which is used to access the first value (ie Male) with name="gender"

You can do the following:

 function validate() { var cbox = document.forms["myForm"]["gender"]; if ( cbox[0].checked == false && cbox[1].checked == false && cbox[2].checked == false ) { alert("Please Select Gender"); return false; } else { alert("Successfully Submited"); return true; } }

 <form onload="return validate()" name="myForm"> <input type="checkbox" name="gender" value="male"> Male <input type="checkbox" name="gender" value="female"> Female <input type="checkbox" name="gender" value="other"> Other <br> <input type="submit" name="submit" value="Submit" onclick="validate()"> </form>

Demo: CodePen

Answer 10

Target it by id and then use this code:

function check(){
    if(document.getElementById('yourid').checked
    {
        return false;
    }
    else
    {
        alert ("checkbox not checked"); 
        return false;
    }
}

Answer 11

var testCheckbox = document.getElementById("checkbox");  
if (!testCheckbox.checked) {
  alert("Error Message!!");
}
else {
  alert("Success Message!!");
}

Answer 12

Guys you can do this kind of validation very easily. Just you have to track the id or name of the checkboxes. you can do it statically or dynamically.

For statically you can use hard coded id of the checkboxes and for dynamically you can use the name of the field as an array and create a loop.

Please check the below link. You will get my point very easily.

http://expertsdiscussion.com/checkbox-validation-using-javascript-t29.html

Thanks