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Force Selection From Checkbox Option

Posted on 2013-01-23
6
Medium Priority
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426 Views
Last Modified: 2013-01-30
Hello,

We have a list of check box options that goe like this as part of a web form:

Please select 3 companies:
(checkbox1)  Company 1
(checkbox2)  Company 2
(checkbox3)  Company 3
(checkbox4)  Company 4
(checkbox5)  Company 5

Here is the sample code
<table>
<tr><td align="right">Please select 3 Companies</td></tr>
<tr><td><input name="chkCompany1" type="checkbox" id="chkCompany1" value="Company 1">Company 1</td></tr>
<tr><td><input name="chkCompany2" type="checkbox" id="chkCompany2" value="Company 2">Company 2</td></tr>
<tr><td><input name="chkCompany3" type="checkbox" id="chkCompany3" value="Company 3">Company 3</td></tr>
<tr><td><input name="chkCompany4" type="checkbox" id="chkCompany4" value="Company 4">Company 4</td></tr>
<tr><td><input name="chkCompany5" type="checkbox" id="chkCompany5" value="Company 5">Company 5</td></tr>   
</table>

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This is what we look to acomplish.

1. The user must select 3 out of the 5 in order to succesfully submit the form.

2. The user should be notified if they do not select any checkbox or if they selected less than 3 when they click on the submit button.

3. If possible, when a user selects 3 checkboxes, the other 2 should grey out.

Thanks!  Your help is much appreciated.
0
Comment
Question by:JParra72
6 Comments
 
LVL 83

Accepted Solution

by:
leakim971 earned 2000 total points
ID: 38812098
test page : http://jsfiddle.net/AHm9u/
window.onload = function() {

    document.getElementById("myform").onsubmit = function() {
		var howManyChecked = nbCheckboxChecked();
        if(howManyChecked!=3) {
            alert("select 3 checkboxes, no more no less!");
        	return false;
        }
        return true;
    }

    var inputs = document.getElementsByTagName("input");
    for(var i=0;i<inputs.length;i++)  if( inputs[i].name && /^chkCompany\d$/.test(inputs[i].name) ) inputs[i].onclick = function() {
        if(nbCheckboxChecked()==3) disableCheckboxes(true);
        else disableCheckboxes(false);
    };
}

function nbCheckboxChecked() {
    n = 0;
	var inputs = document.getElementsByTagName("input");
    for(var i=0;i<inputs.length;i++) if( inputs[i].name && /^chkCompany\d$/.test(inputs[i].name) && inputs[i].checked ) n++; 
    return n;
}

function disableCheckboxes(b) {
	var inputs = document.getElementsByTagName("input");
	for(var i=0;i<inputs.length;i++) if( inputs[i].name && /^chkCompany\d$/.test(inputs[i].name) ) inputs[i].disabled = !inputs[i].checked && b;
}

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0
 
LVL 83

Expert Comment

by:leakim971
ID: 38812134
with jQuery : http://jsfiddle.net/AHm9u/2/
$(document).ready(function() {
    $("form").submit(function(evt) {
        if($(":checkbox[name^=chkCompany]").length != 3) {
            evt.preventDefault();
            alert("select 3 checkboxes, no more no less!");
        }
    })
    $(":checkbox[name^=chkCompany]").change(function() {
        $(":checkbox[name^=chkCompany]:not(:checked)").prop("disabled", ($(":checkbox[name^=chkCompany]:checked").length == 3));
    })
})

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0
 
LVL 18

Expert Comment

by:nap0leon
ID: 38812157
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
	<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
	<title>Q_28006343.html</title>
</head>
<script>
function countCheckmarks() {
	var numCheckedBoxes = 0
	for (var i = 1; i<=5 ; i++) {
		if (document.getElementById('chkCompany'+i).checked == true ) {
			numCheckedBoxes = numCheckedBoxes  + 1;
		}
	}
	return numCheckedBoxes;
}

function validate(){
	var numCheckedBoxes = countCheckmarks()
	if ( numCheckedBoxes == 3 ) {
		document.getElementById('myForm').submit();
	} else {
		alert('You selected ' + numCheckedBoxes + '\nYou need to select 3.');
		return false;
	}

}

function checkMaxChecked() {
	if (countCheckmarks() == 3) {
		for (var i = 1; i<=5 ; i++) {
			if (document.getElementById('chkCompany'+i).checked == false ) {
				document.getElementById('chkCompany'+i).disabled = true;
			}
		}
	} else {
		for (var i = 1; i<=5 ; i++) {
			document.getElementById('chkCompany'+i).disabled = false;
		}
	}
}
</script>

<body>

<form name="myForm" id="myForm" method="GET" action="somenewpage.html">
<table>
	<tr><td align="right">Please select 3 Companies</td></tr>
	<tr><td><input name="chkCompany1" type="checkbox" id="chkCompany1" value="Company 1" onchange="checkMaxChecked();">Company 1</td></tr>
	<tr><td><input name="chkCompany2" type="checkbox" id="chkCompany2" value="Company 2" onchange="checkMaxChecked();">Company 2</td></tr>
	<tr><td><input name="chkCompany3" type="checkbox" id="chkCompany3" value="Company 3" onchange="checkMaxChecked();">Company 3</td></tr>
	<tr><td><input name="chkCompany4" type="checkbox" id="chkCompany4" value="Company 4" onchange="checkMaxChecked();">Company 4</td></tr>
	<tr><td><input name="chkCompany5" type="checkbox" id="chkCompany5" value="Company 5" onchange="checkMaxChecked();">Company 5</td></tr>   
</table>
<input type="button" value="submit" onclick="validate();"/>
</form>                                  

</body>
</html>

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LVL 111

Expert Comment

by:Ray Paseur
ID: 38813032
On the server side in PHP, you can make a test if you change the names of the input controls like this. Instead of  name="chkCompany1", name="chkCompany2", etc.  You can use an array like this:  name="chkCompany[1]", name="chkCompany[2]", etc.

You can use var_dump() to print out the contents of $_POST to see the new data structure.

HTH, ~Ray
0
 

Author Closing Comment

by:JParra72
ID: 38827525
Worked like a charm!
0
 

Author Comment

by:JParra72
ID: 38837441
Hello,

I just noticed it will not work in IE 9 or firefox.

<script language="javascript" type="text/javascript">
window.onload = function() {

    document.getElementById("join_gold_form_c").onsubmit = function() {
		var howManyChecked = nbCheckboxChecked();
        if(howManyChecked!=3) {
            alert("select 3 checkboxes, no more no less!");
        	return false;
        }
        return true;
    }

    var inputs = document.getElementsByTagName("input");
    for(var i=0;i<inputs.length;i++)  if( inputs[i].name && /^chkCompany\d$/.test(inputs[i].name) ) inputs[i].onclick = function() {
        if(nbCheckboxChecked()==3) disableCheckboxes(true);
        else disableCheckboxes(false);
    };
}

function nbCheckboxChecked() {
    n = 0;
	var inputs = document.getElementsByTagName("input");
    for(var i=0;i<inputs.length;i++) if( inputs[i].name && /^chkCompany\d$/.test(inputs[i].name) && inputs[i].checked ) n++; 
    return n;
}

function disableCheckboxes(b) {
	var inputs = document.getElementsByTagName("input");
	for(var i=0;i<inputs.length;i++) if( inputs[i].name && /^chkCompany\d$/.test(inputs[i].name) ) inputs[i].disabled = !inputs[i].checked && b;
}
</script>

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