为什么$（“ ul：first”）。find（“ li”）有效，但是$（“ ul”）[0] .find（“ li”）在jQuery中不起作用？

Question

Does that mean $("ul")[0] is not a jQuery object because it works when I use $($("ul")[0]).find("li") , though it looks a little ugly.

Does anyone have ideas why $("ul")[0] can't be used to find directly?

Answer 1

That's right; a jQuery object acts as an extension of an array of DOM elements. If you access any of them by index, you get a raw DOM object, not another jQuery object. If you want to access a jQuery object for just one of the elements the object represents, use eq :

$('ul').eq(0).find('li')

Answer 2

You're correct -- $("ul")[0] is not a jQuery object. It's a DOM node (an HTMLUListElement , to be precise).

The reason that $($("ul")[0]).find("li") works is that you can construct a jQuery object from a DOM node by passing it as a parameter to the $ function. $("<ul>") , for instance, will make a ul node and wrap it in a jQuery object.

Answer 3

您可以使用$("ul:eq(0)")或$("ul").eq(0)

Answer 4

You can use like this

$("ul").index(0);

or

$("ul").eq(0)


$("ul")[0] is a DOM element

Answer 5

您应该使用$（“ ul”）。eq（0）代替$（“ ul”）[0]