因为你的元素没有被隐藏。把它改成
$(element).hide().fadeIn(500);
// --------^^^^^^^
…或设置
style="display: none"
afterAdd
电话)。
var count = 0;
ko.applyBindings({
myItems: ko.observableArray(['A', 'B', 'C']),
FadeIn: function(element, index, item) {
if (element.nodeType == 1) {
$(element).hide().fadeIn(500);
}
},
addItem: function() {
this.myItems.push('New item');
}
});
<ul data-bind="foreach: { data: myItems, afterAdd: FadeIn }">
<li data-bind="text: $data"></li>
</ul>
<button data-bind="click: addItem">Add</button>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.4.2/knockout-min.js"></script>