waarden van een listbox selecteren

<script language="javascript">
function allSelect( form , element ) 
{
	
	var Select = document.forms[form].elements[element];
	
	for( var i = 0 ; i < Select.length ; i++ ) {
		Select.options[i].selected = true;
	}

}

function deSelect( form , element ) 
{
	
	var Select = document.forms[form].elements[element];
	
	for( var i = 0 ; i < Select.length ; i++ ) {
		Select.options[i].selected = false;
	}

}
</script>

<form name="myForm">
<select name="stations" multiple="multiple" size="3">
<option>first</option>
<option>second</option>
<option>third</option>
</select>

<br />

<input type="button" value="Select all" onClick="allSelect('myForm','stations');">
<input type="button" value="deselect all" onClick="deSelect('myForm','stations');">
</form>

<script language="javascript">
function allSelect( form , element ) 
{
 
	var Select = document.forms[form].elements[element];
 
	for( var i = 0 ; i < Select.length ; i++ ) {
		Select.options[i].selected = true;
	}
 
}
 
function deSelect( form , element ) 
{
 
	var Select = document.forms[form].elements[element];
 
	for( var i = 0 ; i < Select.length ; i++ ) {
		Select.options[i].selected = false;
	}
 
}
</script>
 
<form name="myForm">
<select name="stations" multiple="multiple" size="3">
<option>first</option>
<option>second</option>
<option>third</option>
</select>
 
<br />
 
<input type="button" value="Select all" onClick="allSelect('myForm','stations');">
<input type="button" value="deselect all" onClick="deSelect('myForm','stations');">
</form>