How to make two checkboxes required out of three in HTML? - html

Question

<input type="checkbox" name="Package1" value="packagename">
<input type="checkbox" name="Package2" value="packagename">
<input type="checkbox" name="Package3" value="packagename">
How to make any two checkboxes required for the user to submit the form. The user should not be able to submit the form unless he has checked atleast two checkboxes?
How to achieve that?

Answer 1

Rename checkboxes to name=package[] and values 1, 2, 3.
Then in PHP you'll have o condition (if you send form with GET method, just change POST to GET):
if (isset($_POST['package']) && count($_POST['package']) >= 2) {/* continue */}
If you want to validate it in browser (JS), than:
<script>
var i = 0;
$('[type="checkbox"]').each(function() {
if ($(this).is(':checked')) {
i++;
}
});
if (i <= 1) {
return false; // disable sending form when you've checked 1 checkbox in maximum
}
</script>

Answer 2

Add a class that refers only these checkboxes and then count how many are checked.

Answer 3

A quick and dirty way to validate the checkboxes using JavaScript:
JavaScript
checkCheckboxes = function() {
var numberOfCheckedCheckboxes = 0;
var checkbox1 = document.getElementsByName("Package1")[0];
var checkbox2 = document.getElementsByName("Package2")[0];
var checkbox3 = document.getElementsByName("Package3")[0];
if (checkbox1.checked)
{
numberOfCheckedCheckboxes++;
}
if (checkbox2.checked)
{
numberOfCheckedCheckboxes++;
}
if (checkbox3.checked)
{
numberOfCheckedCheckboxes++;
}
alert(numberOfCheckedCheckboxes >= 2);
}
DEMO: JSFiddle
This code isn't the cleanest block of code, however it does get the job done, and will return true if there are at least 2 checkboxes checked, and will return false otherwise. To make it cleaner, you can change the name value of each checkbox to the same name, such as "packages", and then use document.getElementByName("packages"), then use a for-each loop to loop through each element and check its checked state (I would provide a demo in JSFiddle or JSBin, however it seems that Google Chrome is blocking the script in that case). Using the for-each implementation would allow you to use the same amount of code, regardless of the number of checkboxes.

Answer 4

In HTML, you cannot.
You can impose restrictions in client-side JavaScript or in server-side processing of form data, or both. As usual, client-side restrictions are inherently unreliable and should be regarded as convenience to the user, not a reliable method of doing anything. Server-side processing depends on the server-side technology used.