JS_SetErrorReporter

Get or specify the error reporting mechanism for an application.

Syntax

JSErrorReporter
JS_GetErrorReporter(JSRuntime *rt);
JSErrorReporter
JS_SetErrorReporter(JSRuntime *rt, JSErrorReporter er);
Name Type Description
cx JSRuntime * Pointer to a JS runtime whose errors should be reported via your function. 
er JSErrorReporter The user-defined error reporting function to use in your application, described below.

Callback Syntax

typedef void
(* JSErrorReporter)(JSContext *cx, const char *message, JSErrorReport *report);
Name Type Description
cx JSContext * The context in which the error happened.
message const char * An error message.
report JSErrorReport * An error report record containing additional details about the error.

Description

JS_SetErrorReporter enables you to define and use your own error reporting mechanism in your applications. The reporter you define is automatically passed a JSErrorReport structure when an error occurs and has been parsed by JS_ReportError. JS_SetErrorReporter

JS_GetErrorReporter returns the value set by JS_SetErrorReporter.

Typically, the error reporting mechanism you define should log the error where appropriate (such as to a log file), and display an error to the user of your application. The error you log and display can make use of the information passed about the error condition in the JSErrorReport structure.

The error reporter callback must not reenter the JSAPI. Like all other SpiderMonkey callbacks, the error reporter callback must not throw a C++ exception.

Note that JS_SetErrorReporter has no facility to directly pass a user data pointer to the error reporting function. You can work around this by using the JS_SetRuntimePrivate and JS_GetRuntimePrivate methods. Example code with error handling omitted:

    class MyRequest {
    public:
      void execute() {
        auto rt = JS_NewRuntime(memlimit);
        JS_SetRuntimePrivate(rt, this);
        JS_SetErrorReporter(rt, &MyRequest::dispatchError);
        // execute JS
      }
      void onError(const std::string& error) {
        // handle error
      }
      static void dispatchError(
          JSContext* ctx,
          const char* message,
          JSErrorReport* report) {
        auto rt = JS_GetRuntime(ctx);
        auto rt_userdata = JS_GetRuntimePrivate(rt);
        if (rt_userdata) {
          auto req = static_cast<MyRequest*>(rt_userdata);
          req->onError(message);
        }
      }
    };

 

See Also

Document Tags and Contributors

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 Contributors to this page: yan12125, paulasmuth, arai, fscholz, Jorend, Dria, MMondor
 Last updated by: yan12125,