QML 全局对象

The QML JavaScript host environment implements the following host objects and functions. These are built in and can be used from any JavaScript code loaded in QML, without additional imports:

The Qt object : This object is specific to QML, and provides helper methods and properties specific to the QML environment.
qsTr(), qsTranslate(), qsTrId(), QT_TR_NOOP (), QT_TRANSLATE_NOOP ()，和 QT_TRID_NOOP () functions: These functions are specific to QML, and provide translation capabilities to the QML environment.
gc() function: This function is specific to QML, and provides a way to manually trigger garbage collection.
print() function: This function is specific to QML, and provides a simple way to output information to the console.
The 控制台对象 : This object implements a subset of the FireBug 控制台 API .
XMLHttpRequest , DOMException: These objects implement a subset of the W3C XMLHttpRequest 规范 .

注意： The globalObject() function cannot be used to modify the global object of a QQmlEngine . For more information about this, see JavaScript 环境限定 .

XMLHttpRequest

The XMLHttpRequest object, which can be used to asynchronously obtain data from over a network.

The XMLHttpRequest API implements the same W3C standard as many popular web browsers with following exceptions:

QML 的 XMLHttpRequest does not enforce the same origin policy.

此外， responseXML XML DOM tree currently supported by QML is a reduced subset of the DOM Level 3 Core API supported in a web browser. The following objects and properties are supported by the QML implementation:

Node	Document	元素	Attr	CharacterData	文本
nodeName nodeValue nodeType parentNode childNodes firstChild lastChild previousSibling nextSibling 属性	xmlVersion xmlEncoding xmlStandalone documentElement	tagName	名称值 ownerElement	data length	isElementContentWhitespace wholeText

The XMLHttpRequest example 演示如何使用 XMLHttpRequest object to make a request and read the response headers.