Basic JavaScript - Not getting expected results with else if statement

When I use:

$('.quantity').on('click', '.plus', function(e) {

$input = $(this).prev('input.qty');
var val = parseInt($input.val());

if (val == 1) { 
    $input.val( val=2 ); 
    }
});

I'm getting the result of 2 on click, as expected. However, when I use:

$('.quantity').on('click', '.plus', function(e) {

$input = $(this).prev('input.qty');
var val = parseInt($input.val());

if (val == 1) { 
    $input.val( val=2 ); 
    } else if (val == 2) {
        $input.val( val=3 ); 
    }
});

Even when the starting value is 1, I'm still getting 3 on click (not 2)