Javascript 过滤器数组抛出错误并崩溃

Question

我正在使用 Typescript/JavaScript 编写基于 NativeScript 的移动应用程序。此代码片段在蓝牙扫描完成后调用。我需要找到正确的服务。在我尝试从选项中选择我想要的服务之前，我的代码一直有效。 services.filter(function (obj) { 行似乎导致应用程序崩溃，但错误日志对我来说意义不大...

console.log("Connect Variable");
var services: Array<string>;
var service: any;
services = []; //initialise array
bluetooth.connect(
    {
     UUID: _peripheral.UUID,
     // NOTE: we could just use the promise as this cb is only invoked once
        onConnected: function (peripheral) {
            console.log("------- Peripheral connected: " + JSON.stringify(peripheral));
            // Put all Services into an Array
            peripheral.services.forEach(function (value) {
                console.log("---- ###### adding service: " + value.UUID);
                services.push(value);
            });

            //search for the correct service
            service = peripheral.services.filter(function (obj) { // <- PROBLEM LINE ****************** Caudsing the app to crash out ...
                return obj.UUID == 'A000';
            });
        },
    }
);

这是控制台日志:

CONSOLE LOG file:///app/Pages/Home/home.component.js:145:32: ---- ###### adding service: A000
CONSOLE LOG file:///app/Pages/Home/home.component.js:145:32: ---- ###### adding service: 180A
***** Fatal JavaScript exception - application has been terminated. *****
Native stack trace:
1   0xbea99 NativeScript::FFICallback<NativeScript::ObjCMethodCallback>::ffiClosureCallback(ffi_cif*, void*, void**, void*)
2   0x4ae381 ffi_closure_inner_SYSV
3   0x4b20b8 ffi_closure_SYSV
4   0x25e59d15 <redacted>
5   0x25e59e4b <redacted>
6   0x25e5f9f3 <redacted>
7   0x208d1823 <redacted>
8   0x208d180f <redacted>
9   0x208dfba9 <redacted>
10  0x20d25bdd <redacted>
11  0x20d240d7 <redacted>
12  0x20c732e9 CFRunLoopRunSpecific
13  0x20c730d5 CFRunLoopRunInMode
14  0x22263ac9 GSEventRunModal
15  0x253380b9 UIApplicationMain
16  0x4b202c ffi_call_SYSV
17  0x4ae0c3 ffi_call
18  0x91a0b NativeScript::FFICall::call(JSC::ExecState*)
19  0x2e4931 JSC::LLInt::setUpCall(JSC::ExecState*, JSC::Instruction*, JSC::CodeSpecializationKind, JSC::JSValue, JSC::LLIntCallLinkInfo*)
20  0x2e2579 llint_slow_path_call
21  0x2ea1ed llint_entry
22  0x2ea1f9 llint_entry
23  0x2ea1f9 llint_entry
24  0x2ea4c1 llint_entry
25  0x2ea1f9 llint_entry
26  0x2e5021 vmEntryToJavaScript
27  0x2a4cd9 JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*)
28  0x28d713 JSC::Interpreter::executeCall(JSC::ExecState*, JSC::JSObject*, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&)
29  0x38be87 JSC::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&, WTF::NakedPtr<JSC::Exception>&)
30  0x9e943 NativeScript::GlobalObject::moduleLoaderEvaluate(JSC::JSGlobalObject*, JSC::ExecState*, JSC::JSValue, JSC::JSValue)
31  0x44c4f9 JSC::ModuleLoaderObject::evaluate(JSC::ExecState*, JSC::JSValue, JSC::JSValue)
JavaScript stack trace:
1   onConnected@file:///app/Pages/Home/home.component.js:157:55
2   peripheralDidDiscoverCharacteristicsForServiceError@file:///app/tns_modules/nativescript-bluetooth/bluetooth.js:111:23
3   UIApplicationMain@[native code]
4   start@file:///app/tns_modules/application/application.js:233:26
5   @file:///app/tns_modules/nativescript-angular/application.js:65:26
6   ZoneAwarePromise@file:///app/tns_modules/zone.js/dist/zone-node.js:542:38
7   nativeScriptBootstrap@file:///app/tns_modules/nativescript-angular/application.js:64:23
8   anonymous@file:///app/main.js:5:36
9   evaluate@[native code]
10  moduleEvaluation@[native code]
11  @[native code]
12  promiseReactionJob@[native code]
JavaScript error:

我做错了什么？

更新:

根据 Vladimir 的回答，我得到了这个:

for (let i = 0; i < peripheral.service.count; i++) {
   if (peripheral.services.objectAtIndex(i).UUID == 'A000') {
      service = peripheral.services.objectAtIndex(i);
      console.log("selected service: ");
   }
}

但是，我仍然得到这个输出:

JavaScript error: file:///app/Pages/Home/home.component.js:98:56: JS ERROR TypeError: undefined is not an object (evaluating 'peripheral.service.count')

Answer 1

这很可能是 NSArray 而不是 JavaScript 数组，这就是为什么您不能使用 filter() 的原因。可能的解决方案是循环 native NSArray 并仅复制需要的对象，或者您可以复制所有对象并稍后使用 filter。这是一个如何复制所有对象的示例:

var services = [];
for (let i = 0; i < peripheral.services.count; i++) {
   services.push(peripheral.services.objectAtIndex(i));
}