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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第五章
繫結機制（Binding）
學會繫結機制，才能真正體會從用戶端產生檢視器的好處。繫結指的是把檢視器元件和
JavaScript 物件（通常是模型）綁在一起。當 JavaScript 物件的內容有變動時，檢視器也
會自動同步更新相關內容。也就是說，把檢視器和模型綁在一起後，只要模型有變動，
就會自動重新產生新的檢視器內容。
繫結可說是非常重要的功能。有了這項功能，就不需要在資料異動時，透過控制器去更
新檢視器內容，一切都會自動完成。此外，善用繫結機制管理應用程式，也可說是為建
立即時應用程式（請參閱本書第八章）舖路。
如果要把 JavaScript 物件和檢視器綁在一起，就得在物件的屬性有異動時，透過一
個回叫函式來觸發檢視器的更新。但 JavaScript 並沒有內建這樣的函式（像 Ruby 或
Python，就有提供類似
method_missing
的功能），而且目前也沒辦法利用 JavaScript
的取值函式（getter）和設值函式（setter）（
http://ejohn.org/blog/javascript-getters-and-
setters
）模擬出類似的功能。不過由於 JavaScript 是一種非常有彈性的程式語言，因此
還是能自行開發出
change
回叫函式：
var addChange = function(ob){
ob.change = function(callback){
if (callback) {
if ( !this._change ) this._change ...
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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.
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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.