update 02/21 and 03/10

This commit is contained in:
numbbbbb
2014-06-10 12:14:55 +08:00
parent 7d716b5daf
commit 9eddc9af5a
41 changed files with 637 additions and 184 deletions

View File

@ -46,7 +46,7 @@
<div class="book" data-level="2.17" data-basepath=".." data-revision="1402328527093">
<div class="book" data-level="2.17" data-basepath=".." data-revision="1402373659943">
<div class="book-header">
<!-- Actions Left -->
<a href="#" class="btn pull-left toggle-summary" aria-label="Toggle summary"><i class="fa fa-align-justify"></i></a>
@ -587,7 +587,7 @@
<div class="page-inner">
<section class="normal" id="section-gitbook_39">
<section class="normal" id="section-gitbook_36">
<h1 id="optional-chaining">Optional Chaining</h1>
<p>可选链Optional Chaining是一种可以请求和调用属性、方法及子脚本的过程它的自判断性体现于请求或调用的目标当前可能为空<code>nil</code>)。如果自判断的目标有值,那么调用就会成功;相反,如果选择的目标为空(<code>nil</code>),则这种调用将返回空(<code>nil</code>)。多次请求或调用可以被链接在一起形成一个链,如果任何一个节点为空(<code>nil</code>)将导致整个链失效。</p>