JSObjectOps.getProperty 编辑

Obsolete since JavaScript 1.8.5
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

Warning! JSObjectOps is not a supported API. Details of the API may change from one release to the next. This documentation should be considered SpiderMonkey internals documentation, not API documentation. See bug 408416 for details.

JSObjectOps.getProperty, setProperty, and deleteProperty are high-level callbacks that implement object property accesses.

Each of these callbacks is responsible for everything involved with an individual property access operation, including: any locking necessary for thread safety; security checks; finding the property, including walking the prototype chain if needed; calling the lower-level JSClass hooks; calling getters or setters; and actually getting, setting, or deleting the property once it is found.

Contrast JSClass.getProperty, JSClass.setProperty, and JSClass.delProperty, which are hooks called during property accesses and don't have to implement any of that.

Syntax

typedef JSBool (*JSPropertyIdOp)(
    JSContext *cx, JSObject *obj, jsid id, jsval *vp);

Description

Get, set, or delete obj[id], returning JS_FALSE on error or exception, JS_TRUE on success. If getting or setting, the new value is returned in *vp on success.

If deleting without error, *vp will be JSVAL_FALSE if obj[id] is permanent, and JSVAL_TRUE if id named a direct property of obj that was in fact deleted, or if id names no direct property of obj (id could name a property of a prototype, or no property in obj or its prototype chain). This reflects the quirky behavior of delete as specified in ECMA 262-3 §11.4.1 and ECMA 262-3 §8.6.2.5.