通过脚本_spPageContextInfo获取当前SharePoint上下文信息

_spPageContextInfo，一段非常有用的SharePoint JavaScript代码，通过它可以很方便获取当前页面的相关信息。

Name	SP2007	SP2010	SP2013	Example Value
alertsEnabled		X	X	false
allowSilverlightPrompt		X	X	true
clientServerTimeDelta			X	17856
crossDomainPhotosEnabled			X	true
currentCultureName			X	en-US
currentLanguage		X	X	1033
currentUICultureName			X	en-US
L_Menu_BaseUrl	X	X	X	/Sites/Demos
layoutsUrl			X	_layouts/15
pageItemId		X	X	1
pageListId		X	X	GUID
pagePersonalizationScope			X	1
serverRequestPath			X	/Sites/Demos/SitePages/Home.aspx
siteAbsoluteUrl			X	http://sharepoint.com
siteClientTag			X	21$$15.0.4454.1026
siteServerRelativeUrl			X	/sites/Demos
systemUserKey			X	1:0).w|<sid>
tenantAppVersion			X	0
userId		X	X	30
webAbsoluteUrl			X	http://sharepoint.com/sites/demos
webLanguage		X	X	1033
webLogoUrl			X	_layouts/15/images/siteicon.png
webPermMasks			X	Object with properties High & Low
webServerRelativeUrl		X	X	/Sites/Demos
webTemplate			X	1
webTitle			X	Demos
webUIVersion		X	X	4 (2010) or 15 (2013)

下面是一段简单的代码创建了一个带有图片的超链接，当点击超链接时会跳到当前Site Collection首页

<A onclick="window.location = _spPageContextInfo.siteAbsoluteUrl;">    
<IMG class=logo alt="W Logo" src="/_layouts/15/ProjectFeature_7949818d75c64017bf5008b1391486e1/Images/wLogo.png">
</A>