Package com.google.gwt.core.client

Class JavaScriptObject

java.lang.Object

com.google.gwt.core.client.JavaScriptObject

Direct Known Subclasses:

ArrayBufferNative, ArrayBufferViewNative, CanvasPixelArray, Context2d, DataTransfer, EventTarget, FillStrokeStyle, ImageData, JsArray, JsArrayBoolean, JsArrayInteger, JsArrayMixed, JsArrayNumber, JsArrayString, JsDate, MediaError, NativeEvent, Node, NodeCollection, NodeList, PositionImpl, PositionImpl.CoordinatesImpl, StorageEvent, Style, TextMetrics, TimeRanges, TimeZoneInfo, Touch, XMLHttpRequest

public class JavaScriptObject
extends Object

An opaque handle to a native JavaScript object. A JavaScriptObject cannot be created directly. JavaScriptObject should be declared as the return type of a JSNI method that returns native (non-Java) objects. A JavaScriptObject passed back into JSNI from Java becomes the original object, and can be accessed in JavaScript as expected.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	JavaScriptObject()	Not directly instantiable.

Method Summary

Modifier and Type	Method	Description
final <T extends JavaScriptObject> T	cast()	A helper method to enable cross-casting from any JavaScriptObject type to any other JavaScriptObject type.
static JavaScriptObject	createArray()	Returns a new array.
static JavaScriptObject	createArray(int size)	Returns a new array with a given size.
static JavaScriptObject	createFunction()	Returns an empty function.
static JavaScriptObject	createObject()	Returns a new object.
final boolean	equals(Object other)	Calls a native JS equals method if any, otherwise returns true if the objects are JavaScript identical (triple-equals).
final int	hashCode()	Calls a native JS hashCode method if any, otherwise uses a monotonically increasing counter to assign a hash code to the underlying JavaScript object.
String	toSource()	Call the toSource() on the JSO.
final String	toString()	Makes a best-effort attempt to get a useful debugging string describing the given JavaScriptObject.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

JavaScriptObject

protected JavaScriptObject()

Not directly instantiable. All subclasses must also define a protected, empty, no-arg constructor.

Method Details

createArray

public static JavaScriptObject createArray()

Returns a new array.

createArray

public static JavaScriptObject createArray(int size)

Returns a new array with a given size.

Consider using this method in performance critical code instead of using createArray(), since this gives more hints to the underlying JavaScript VM for optimizations.

createFunction

public static JavaScriptObject createFunction()

Returns an empty function.

createObject

public static JavaScriptObject createObject()

Returns a new object.

cast

public final <T extends JavaScriptObject> T cast()

A helper method to enable cross-casting from any JavaScriptObject type to any other JavaScriptObject type.

Type Parameters:

T - the target type

Returns:

this object as a different type

equals

public final boolean equals(Object other)

Calls a native JS equals method if any, otherwise returns true if the objects are JavaScript identical (triple-equals).

Overrides:

equals in class Object

hashCode

public final int hashCode()

Calls a native JS hashCode method if any, otherwise uses a monotonically increasing counter to assign a hash code to the underlying JavaScript object. Do not call this method on non-modifiable JavaScript objects.

Overrides:

hashCode in class Object

Returns:

the hash code of the object

toSource

public String toSource()

Call the toSource() on the JSO.

toString

public final String toString()

Makes a best-effort attempt to get a useful debugging string describing the given JavaScriptObject. In Production Mode with assertions disabled, this will either call and return the JSO's toString() if one exists, or just return "[JavaScriptObject]". In Development Mode, or with assertions enabled, some stronger effort is made to represent other types of JSOs, including inspecting for document nodes' outerHTML and innerHTML, etc.

Overrides:

toString in class Object