订单对象是否由指定的 jQuery 选择器返回?

所有 jQuery 选择器都返回一个对象数组。这些对象是否总是按照 HTML 中的顺序排列?我能相信吗?

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Yes, they're always in the order as they're in the DOM.

Probably in the order it finds them, a selector pretty much traverses the DOM and when it finds an element that matches, puts it in an array.

You could maybe do a test by having say 5 textboxes with id's of "textbox_n" where n is a number, then alert the list and see what you get?

Yes.
The jQuery 1.3.2 release notes say:

Elements Returned in Document Order

This is a change to jQuery's selector engine that re-orders the returned results to be in document order, instead of the order in which the selectors were passed in. This change was done in order to be in compliance with the Selectors API specification (which jQuery uses, internally, in browsers that support it).

This wasn't the case on jQuery 1.3:

The order of "a, b, c" style selectors may change. Browsers that support querySelectorAll (Safari, Firefox 3.5+, Opera 10+, IE 8+) will return the elements in document order, other browsers will (currently) return them in the order specified. In 1.3.2 and later release all comma-separated selectors will be returned in document order.

There may be some exceptions, for example from the prevAll() documentation:

"Given a jQuery object that represents a set of DOM elements, the .prevAll() method searches through the predecessors of these elements in the DOM tree and construct a new jQuery object from the matching elements; the elements are returned in order beginning with the closest sibling."

http://api.jquery.com/prevAll/