为什么括号表示法似乎比jQuery对象访问更多数据？

Question

I'm still trying to understand the difference between $('foo')[0] and $('foo').eq(0) .

As I understand it, the second one should access a jQuery object so I can use jQuery methods without having to wrap it again.

My question is this. Why does this (using "QuickWatch" in VS) seem to return direct access to the object, meaning that I can instantly access its properties:

$(this).children('SPAN')[0]

But when I use this, I get access to "prototype", "context", "prevObject", etc. and "[0]":

$(this).children('SPAN').eq(0)

With the second method, it looks as though I'd still have to use [0] to get access to the various properties?

I hope this makes sense, but I am trying to figure out the most elegant syntax.

**Edited: - Not to beat this to death, but I changed the title to make more sense. The original title was "...are they the same?" And of course, the two things aren't the same.

Answer 1

In your case the children() returns an array like object where you access the item on index 0 which is a raw DOM node.

To get the same effect with .eq() (which wraps the DOM node to a jQuery object) you would have to "evaluate it", ie. call [0] on it. If you want the same effect as the children()[0] call but not do eq(0)[0] , use .get(0) instead.

Answer 2

They are not the same. eq() is a jQuery function. [] accesses the array of jQuery objects directly.

One advantage of using eq() is it will work defensively.

For example:

<li>1</li>
<li>2</li>
<li>3</li>

If you do $('li').eq(4).text() you get nothing. $('li').eq(-1).text() gives you 3.

I recommend using eq() just to make sure.