Javascript 这个函数中的问号是什么意思？
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What does the question mark mean in this function?
提问by user784637
Here's the documentation for this plugin (There's only two functions.) http://tkyk.github.com/jquery-history-plugin/#documentation
这是这个插件的文档（只有两个功能。） http://tkyk.github.com/jquery-history-plugin/#documentation
$(document).ready(function() {
function load(num) {
$('#content').load(num +".html");
}
$.history.init(function(url) {
load(url == "" ? "1" : url);
});
$('#ajax-links a').live('click', function(e) {
var url = $(this).attr('href');
url = url.replace(/^.*#/, '');
$.history.load(url);
return false;
});
});
Here's the html:
这是html：
<body>
<h1>jQuery History Plugin Ajax Sample</h1>
<div id="ajax-links">
<ul>
<li><a href="#1">load 1.html</a></li>
<li><a href="#2">load 2.html</a></li>
<li><a href="#3">load 3.html</a></li>
</ul>
<div id="content"></div>
<hr />
</div>
<p>[<a href="../">All samples</a>] [<a href="http://github.com/tkyk/jquery-history-plugin">Project home</a>]</p>
</body>
回答by foxy
load(url == "" ? "1" : url);
The question mark here is a a ternary if operation, Simply put, it is a short, inline ifstatement.
这里的问号是一个三元的 if 操作，简单来说就是一个简短的内联if语句。
Expanded out, the statement would look something like this:
展开后，该语句将如下所示：
if (url == "")
load("1");
else
load(url);
If the statement before the question mark evaluates to true, then the left-hand side of the colon is used, otherwise (if it is false) the right-hand side is used. You can also nest this, though it isn't always a good idea (for readability).
如果问号前的语句求值为真，则使用冒号的左侧，否则（如果为假）使用冒号的右侧。您也可以嵌套它，尽管它并不总是一个好主意（为了可读性）。
回答by Curt
Its shorthand for:
它的简写：
If (url == ""){
load("1");
}
else {
load(url);
}
Ie. If urlequals ""then return "1", otherwise, return url
IE。如果url等于""则返回"1"，否则返回url
In your example, if the urlequals ""then, 1.htmlwill be loaded, otherwise, url + ".html"will be loaded
在你的榜样，如果url等号""的话，1.html将被加载，否则，url + ".html"将被载入
回答by Sjoerd
It is a ternary operation.
这是一个三元运算。
