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JS_SetContextCallback 编辑

Specifies a callback function that is automatically called whenever a JSContext is created or destroyed.

Syntax

void
JS_SetContextCallback(JSRuntime *rt, JSContextCallback cxCallback, void *data);

Name	Type	Description
`rt`	`JSRuntime *`	Pointer to a JS runtime.
`cxCallback`	`JSContextCallback`	Pointer to the callback function, described below.
`data`	`void *`	Any data passed as 3rd argument to the callback function. Added in SpiderMonkey 31

Callback syntax

typedef bool
(* JSContextCallback)(JSContext *cx, unsigned contextOp, void *data);

Name	Type	Description
`cx`	`JSContext *`	Pointer to a `JSContext` which the callback may use to call into JSAPI functions. This is the context which was just created, or is about to be destroyed. For example, the callback my call `JS_GetContextPrivate`(cx) in order to free up resources previously allocated by `JS_SetContextPrivate`.
`contextOp`	`unsigned`	See `JSContextOp`. For future compatibility the callback must do nothing and return `true` if any other value is passed.
`data`	`void *`	`data` specified in `JS_SetContextCallback`. Added in SpiderMonkey 31

typedef enum JSContextOp {
    JSCONTEXT_NEW,
    JSCONTEXT_DESTROY
} JSContextOp;

Enumeration	Meaning
`JSCONTEXT_NEW`	`JS_NewContext` successfully created a new `JSContext` instance. The callback can initialize the instance as required. If the callback returns `JS_FALSE`, the instance will be destroyed and `JS_NewContext` returns `NULL`. In this case the callback is not called again.
`JSCONTEXT_DESTROY`	One of `JS_DestroyContext`, `JS_DestroyContextNoGC`, or `JS_DestroyContextMaybeGC` was called. The callback may perform its own cleanup and must always return `true`. In a `DEBUG` build, if the callback returns `false`, the JS engine will halt with an assertion.

JS_SetContextCallback specifies a callback function that is automatically called when JSContexts are created or destroyed. Only one callback function may be specified per JS runtime. This function returns the previous context callback, if any, else NULL.

JS_SetContextCallback 编辑

Syntax

Callback syntax

Description

See Also

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友情链接

JS_SetContextCallback 编辑

Syntax

Callback syntax

Description

See Also

如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

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友情链接

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。