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JSResolveOp is the type of the JSClass.resolve.
Syntax
typedef bool
(* JSResolveOp)(JSContext *cx, JS::HandleObject obj,
JS::HandleId id, bool *resolvedp); // Added in JSAPI 36
typedef bool
(* JSResolveOp)(JSContext *cx, JS::HandleObject obj,
JS::HandleId id); // Obsolete since JSAPI 36
| Name | Type | Description |
|---|---|---|
cx |
JSContext * |
Pointer to the JS context in which the property access is taking place. |
obj |
JS::HandleObject |
Pointer to the object whose properties are being accessed. |
id |
JS::HandleId |
The name or index of the property being resolved. |
resolvedp |
bool * |
Out parameter. Receives the result of resolve operation. |
Description
JSResolveOp callback is a hook which is called when a property is not found on an object.
It resolves a lazy property named by id in obj by defining it directly in obj. Lazy properties are those reflected from some peer native property space (e.g., the DOM attributes for a given node reflected as obj) on demand.
The callback must set *resolvedp to true and return true if the property is resolved, or set *resolvedp to false and return true if the object has no lazy property with the given id; or return false to indicate any other error.
Obsolete since JSAPI 36
The callback must return true if the property is resolved, or if the object has no lazy property with the given id; or false to indicate any other error.
Note: JSNewResolveOp provides a cheaper way to resolve lazy properties.
JSClass hooks
JSClass offers the following hook:
JSClass.resolvecallback is called when a property is not found on an object. It can be used to implement lazy properties.JS looks for a property in an object, and if not found, tries to resolve the given
id. After callingresolve, the engine looks again to see ifresolvedefinedobj[id]. If so, the property lookup succeeds. If not, the process is repeated withobj's prototype.