checkbox checker

newbie here guys...

I have 3 checkbox form field and i need a script to prompt for error if user doesn't click on any of the 3 cbox's.

 

<script language="javascript" type="text/javascript">
function checkbox() {

var checklength=document.myForm.needs.length;  // This is the total number of checkboxes you have.
var thebox;
var checked = false; // By default, lets just say that no checkboxes have been checked.

var i=0;

for (i=0;i<=checklength;i++) {   // Lets loop through all the checkboxes called needs.

thebox=document.myForm.needs[i];

if (thebox.checked == true){   //If this needs box is checked, let's note it.
checked=true;
return (true);
}


if (i == checklength - 1) {   // Is this the last checkbox to check?

if (checked == false) {  // If there are no checked boxes, lets alert the user...
alert("Please Make A Selection.");
return (false);  // Return to the page and don't finish the submission process.
}else{
return (true);
}


}
}

}
</script>
<form onsubmit="return checkbox();" name="myForm">

<input type="checkbox" name="needs" value="Web Design" />Web Design<br />

<input type="checkbox" name="needs" value="Web Hosting" />Web Hosting<br />

<input type="checkbox" name="needs" value="Web Promotion" />Web Promotion<br />

<input type="submit" value="Submit" />
</form>

Code (markup):

Hope this helps.

 

thanks.. one more... how about with same question (3 checkbox) with a list menu?

 

<script language="javascript" type="text/javascript">
function checkbox() {
if (document.myForm.mylist.value == '') {
alert("Please select from the dropdown menu.");
return(false);
}
var checklength=document.myForm.needs.length;  // This is the total number of checkboxes you have.
var thebox;
var checked = false; // By default, lets just say that no checkboxes have been checked.

var i=0;

for (i=0;i<=checklength;i++) {   // Lets loop through all the checkboxes called needs.

thebox=document.myForm.needs[i];

if (thebox.checked == true){   //If this needs box is checked, let's note it.
checked=true;
return (true);
}


if (i == checklength - 1) {   // Is this the last checkbox to check?

if (checked == false) {  // If there are no checked boxes, lets alert the user...
alert("Please Make A Selection.");
return (false);  // Return to the page and don't finish the submission process.
}else{
return (true);
}


}
}

}
</script><form onsubmit="return checkbox();" name="myForm">

<input type="checkbox" name="needs" value="Web Design" />Web Design<br />

<input type="checkbox" name="needs" value="Web Hosting" />Web Hosting<br />

<input type="checkbox" name="needs" value="Web Promotion" />Web Promotion<br /><br />
<select name="mylist">
<option selected="selected"></option>
<option value="Web Design">Web Design</option>
<option value="Web Hosting">Web Hosting</option>
<option value="Web Promotion">Web Promotion</option>
</select><br />
<br />


<input type="submit" value="Submit" />
</form>

Code (markup):

I'm assuming you meant a select list dropdown... Hope this helps.

 

thanks!


last one... what if the field names of the checkbox's are different? how is the javascript coding of it?

 

Try this.

	function funcCheck()
	{
		var isOK = false
		var y = document.getElementsByTagName("input");
		for (i=0;i<y.length;i++)
		{
			if(y[i].type=="checkbox"&&y[i].checked==true) {isOK = true;}
		}
		if(isOK)
		{
			alert("OK");
		}
		else
		{
			alert("Error");
		}
	}

Code (markup):