January 2013
Intermediate to advanced
332 pages
5h 23m
Chinese
Content preview from JAVASCRIPT網頁應用程式設計
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第七章
for (var i=0; i < files.length; i++)
assert( files[i].type.match(/image.*/) )
});
其實，取得這些被選取檔案的資訊，用途並不只侷限於進行驗證。還可以讓使用者在
上傳檔案的同時，預覽檔案內容。此外，如果不希望在上傳檔案時鎖死 UI，可以透過
Ajax 程式來上傳檔案，同時還能顯示目前上傳進度。這些做法都會在稍後一一介紹。
拖曳與置放（Drag and Drop）
拖曳 / 置放功能，最早是由 Microsoft 於 1999 年所「設計」，並實作於 IE 5.0 當中，
IE 自此就一直有支援此功能。HTML5 也已將這項功能納入其規格中，現今 Safari、
Firefox，以及 Chrome 等瀏覽器都有仿照微軟的實作，新增此功能。不過坦白說，這份
規格的內容可說是一團混亂（
http://www.quirksmode.org/blog/archives/2009/09/the_html5_
drag.html
），程式設計師往往需要費一番功夫，才能滿足這份規格中一些莫名其妙的
需求。
和拖曳 / 置放功能相關的事件，至少有七個：
dragstart
、
drag
、
dragover
、
dragenter
、
dragleave
、
drop
，以及
dragend
。本書將會在稍後的章節逐一詳加介紹。
即使你所使用的瀏覽器不支援 HTML5 的檔案 API，也有機會能使用拖曳 / 置放功能
API。目前支援拖曳 / 置放功能的瀏覽器有： ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.