I did a solution's example for your problem. If you prefer I putted it in JSBin
Given that you have this HTML:
<div class="unknownSelectable">
<input type="checkbox" value="0" name="Anything" id="Anything1" />
<label for="Anything1">Unknown</label>
<input type="checkbox" value="0" name="Anything" id="Anything2" />
<label for="Anything2">Label 1</label>
<input type="checkbox" value="0" name="Anything" id="Anything3" />
<label for="Anything3">Label 2</label>
<input type="checkbox" value="0" name="Anything" id="Anything4" />
<label for="Anything4">Label 3</label>
</div>
<h1>Select</h1>
<div class="unknownSelectable">
<input type="checkbox" value="0" name="AnotherAnything" id="AnotherAnything1" />
<label for="AnotherAnything1">Unknown</label>
<input type="checkbox" value="0" name="AnotherAnything" id="AnotherAnything2" />
<label for="AnotherAnything2">Label 1</label>
<input type="checkbox" value="0" name="AnotherAnything" id="AnotherAnything3" />
<label for="AnotherAnything3">Label 2</label>
<input type="checkbox" value="0" name="AnotherAnything" id="AnotherAnything4" />
<label for="AnotherAnything4">Label 3</label>
</div>
Just put this Javascript that everything will work:
$( ".unknownSelectable input" ).change(function( event ){
var labelSelected = $( this ).next().html();
if ( labelSelected == "Unknown" ) {
var $siblings = $( this ).siblings( "input[type='checkbox']" );
if( $( this ).is( ":checked" ) )
$siblings.prop( "checked", false );
else
$siblings.prop( "checked", true );
}
});
I changed the event from click to change because it doesn't matter if you click on the input or on the label. I also wrapped it in a div element but this no matter, you can wrap it in another HTML element as well.
Sorry my English, if I did some English mistakes, please, feel free to re-write and improve it.