javascript - JQuery .next() 没有找到下一个兄弟

Answer 1

.next() will try to fetch only the next element if it satisfies the given selector, in your second case the next sibling is not the showDescription element

$('.more').click(function () {
    $(this).html(function (_, html) {
        return $.trim(html) == '▼' ? '▲' : '▼'
    }).nextAll('.showDescription').first().stop().fadeToggle();
});

Demo: Fiddle

Answer 2

.next will only look at the one directly next, it won't look at all ones next. You want .nextUntil.

$('.more').click(function() {
    $(this).html($(this).html()=='▼'?'▲':'▼').nextUntil('.more', '.showDescription').stop().fadeToggle();
});

DEMO: http://jsfiddle.net/vDPZH/10/