Why is this not a valid, chained function?

$("#infoBox").hide(, function(){
            alert('hidden!');
        });

Just a sm开发者_StackOverflowall question, but my code breaks when I try to do this -

You cannot simply omit the first parameter. You need to supply a value for it e.g.:

$("#infoBox").hide('slow', function(){
    alert('hidden!');
});

See the API page for information on what available values there are for the first parameter (duration).

change this to

$("#infoBox").hide('slow', function(){
            alert('hidden!');
        });

jQuery will work out what do do if you omit the speed argument in this case

$( "#infoBox" ).hide( function() {
    alert( 'hidden!' );
});