javascript - SystemJS 对不存在的文件发出约 200 个请求

Question

我真的很迷茫。当我加载我的 Angular2 应用程序时，我有大约 200 个请求到我的服务器以获取 node_modules/systemjs 下不存在的文件。以下是这些请求的示例:

127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/Subject.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/Observable.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/root.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/toSubscriber.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/Subscriber.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/isFunction.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/Subscription.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/isArray.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/isObject.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/tryCatch.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/errorObject.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/UnsubscriptionError.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/Observer.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/rxSubscriber.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/observable.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/ObjectUnsubscribedError.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/SubjectSubscription.js.map HTTP/1.1" 404 -
127.0.0.1 - - [13/Sep/2016 13:00:06] "GET /node_modules/systemjs/dist/from.js.map HTTP/1.1" 404 -

我的 Angular2 应用程序运行良好，没有出现任何错误，一切都按预期运行。但是那些 ~200 404 请求确实减慢了页面加载速度。出于我真的无法理解的原因，那些 404 请求甚至没有出现在我浏览器的 network 选项卡中，但 Wireshark 确认它们来自那里。

这是我的systemjs.config.js:

/**
 * System configuration for Angular 2 samples
 * Adjust as necessary for your application needs.
 */
(function (global) {
  System.config({
    defaultJSExtensions: true,
    paths: {
      // paths serve as alias
      'npm:': 'node_modules/'
    },
    // map tells the System loader where to look for things
    map: {
      // our app is within the app folder
      app: 'app',
      // angular bundles
      '@angular/core': 'npm:@angular/core/bundles/core.umd.js',
      '@angular/common': 'npm:@angular/common/bundles/common.umd.js',
      '@angular/compiler': 'npm:@angular/compiler/bundles/compiler.umd.js',
      '@angular/platform-browser': 'npm:@angular/platform-browser/bundles/platform-browser.umd.js',
      '@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic/bundles/platform-browser-dynamic.umd.js',
      '@angular/http': 'npm:@angular/http/bundles/http.umd.js',
      '@angular/router': 'npm:@angular/router/bundles/router.umd.js',
      '@angular/forms': 'npm:@angular/forms/bundles/forms.umd.js',
      // angular testing umd bundles
      '@angular/core/testing': 'npm:@angular/core/bundles/core-testing.umd.js',
      '@angular/common/testing': 'npm:@angular/common/bundles/common-testing.umd.js',
      '@angular/compiler/testing': 'npm:@angular/compiler/bundles/compiler-testing.umd.js',
      '@angular/platform-browser/testing': 'npm:@angular/platform-browser/bundles/platform-browser-testing.umd.js',
      '@angular/platform-browser-dynamic/testing': 'npm:@angular/platform-browser-dynamic/bundles/platform-browser-dynamic-testing.umd.js',
      '@angular/http/testing': 'npm:@angular/http/bundles/http-testing.umd.js',
      '@angular/router/testing': 'npm:@angular/router/bundles/router-testing.umd.js',
      '@angular/forms/testing': 'npm:@angular/forms/bundles/forms-testing.umd.js',
      // other libraries
      'rxjs':                       'npm:rxjs',
      'angular2-in-memory-web-api': 'npm:angular2-in-memory-web-api',
      'moment':                     'npm:moment/moment',
      'ng2-bs3-modal':              'npm:ng2-bs3-modal',
    },
    // packages tells the System loader how to load when no filename and/or no extension
    packages: {
      app: {
        main: './main.js',
        defaultExtension: 'js'
      },
      rxjs: {
        defaultExtension: 'js'
      },
      'angular2-in-memory-web-api': {
        main: './index.js',
        defaultExtension: 'js'
      },
    }
  });
})(this);

Answer 1

您看到的是您的浏览器请求 source maps ，充当“字典”的文件，将转换后的代码(如转译或缩小)转换为转换前的形式。当您打开调试器并启用源映射支持时，这通常会启动。。这是正常行为。如果您关闭调试器并重新加载您的应用程序，源映射请求将不会发生。

但是，您的应用似乎在错误的位置请求源 map 。那些看起来像第三方库在 systemjs 模块目录中寻找它们的源映射。请参阅有关如何处理路径的 systemjs 文档。