Question

Code is as shown below.

$('p:first').toggle(function() {
$(this).animate({'height':'+=150px'}, 2000, 'linear');
}, function() {
$(this).animate({'height':'-=150px'}, 2000, 'swing');
});

Answer 1

If you change both attributes to “150px” by removing the += and the -=, then both sides of your toggle are animating to the same height so there will be no visual movement. It might move to 150px when you first hover, but then it won’t move again.

The point of the +=150px is to add 150px to the existing height whatever it is. The point of the -=150px is to subtract 150px from the existing height (thus reversing the prior addition).

If you want to remove the += and the -=, then you need to set two different heights in the two arms of the toggle to define the two sizes that you want to toggle between.