JavaScript-1.5 Reference

JS_DefineProperty

Function

Summary

Creates a single property for a specified object.

Syntax

JSBool) JS_DefineProperty(JSContext *cx, JSObject *obj,
    const char *name, jsval value, JSPropertyOp getter,
    JSPropertyOp setter, uintN flags);

Name	Type	Description
`cx`	`JSContext *`	Pointer to a JS context from which to derive runtime information.
`obj`	`JSObject *`	Object for which to create the new property.
`name`	`const char *`	Name for the property to create.
`value`	`jsval`	Initial value to assign to the property.
`getter`	`JSPropertyOp`	`getProperty` method for retrieving the current property value.
`setter`	`JSPropertyOp`	`setProperty` method for specifying a new property value.
`flags`	`uintN`	Property flags.

Description

JS_DefineProperty defines a single property in a specified object, obj.

name is the name to assign to the property in the object. value is a jsval that defines the property's data type and initial value. getter and setter identify the getProperty and setProperty methods for the property, respectively. If you pass null values for these entries, JS_DefineProperties assigns the default getProperty and setProperty methods to this property. flags contains the property flags to set for the newly created property. The following table lists possible values you can pass in flags, either singly, or OR'd together:

Flag Purpose

JSPROP_ENUMERATE
Property is visible in for and in loops.

JSPROP_READONLY
Property is read only.

JSPROP_PERMANENT
Property cannot be deleted.

JSPROP_EXPORTED
Property can be imported by other objects.

JSPROP_INDEX
Property is actually an index into an array of properties, and is cast to a const char *.

If it successfully creates the property, JS_DefineProperty returns JS_TRUE. If the property already exists, or cannot be created, JS_DefineProperty returns JS_FALSE.

Notes

While you can assign a setProperty method to a property and set flags to JSPROP_READONLY, the setter method will not be called on this property.

JavaScript-1.5 Reference

Summary

Syntax

Description

Notes

See Also