在angular2中使用angular-cli获取http:// localhost:4200/null 404(未找到)

Question

在angular2中使用angular-cli获取http:// localhost:4200/null 404(未找到)

我正在使用angular-cli的angular2项目.今天我将下面的版本更新到2.4.1.

"@angular/common": "~2.4.1",
"@angular/compiler": "~2.4.1",
"@angular/compiler-cli": "^2.4.1",
"@angular/core": "~2.4.1",
"@angular/forms": "~2.4.1",
"@angular/http": "~2.4.1",
"@angular/platform-browser": "~2.4.1",
"@angular/platform-browser-dynamic": "~2.4.1",
"@angular/router": "~3.4.1",
"angular-cli": "^1.0.0-beta.24"

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当我使用2.0.0时,它不会出错,但现在,它会出现错误GET http://localhost:4200/null 404 (Not Found).

尽管它出错了,但它运行良好.但是,我想知道它为什么会发生,并修复此错误.如果有人知道这件事,请告诉我.谢谢 :)

Packages.json

{
  ...
  
  "private": true,
  "dependencies": {
    "@angular/common": "~2.4.1",
    "@angular/compiler": "~2.4.1",
    "@angular/compiler-cli": "^2.4.1",
    "@angular/core": "~2.4.1",
    "@angular/forms": "~2.4.1",
    "@angular/http": "~2.4.1",
    "@angular/material": "^2.0.0-beta.0",
    "@angular/platform-browser": "~2.4.1",
    "@angular/platform-browser-dynamic": "~2.4.1",
    "@angular/router": "~3.4.1",
    "@types/moment-timezone": "^0.2.33",
    "angular-cli": "^1.0.0-beta.24",
    "angular2-google-maps": "^0.17.0",
    "bootstrap": "^3.3.7",
    "bourbon": "^4.2.7",
    "core-js": "^2.4.1",
    "es6-promise": "^4.0.5",
    "font-awesome": "^4.7.0",
    "hammerjs": "^2.0.8",
    "moment": "^2.17.1",
    "moment-timezone": "^0.5.10",
    "node-sass": "^3.13.0",
    "primeng": "^1.1.0",
    "pubnub-angular2": "^1.0.0-beta.6",
    "quill": "^1.1.8",
    "rxjs": "5.0.1",
    "ts-helpers": "^1.1.1",
    "typescript": "^2.0.10",
    "typings": "^2.1.0",
    "zone.js": "^0.7.4"
  },
  "devDependencies": {
    "@types/hammerjs": "^2.0.33",
    "@types/jasmine": "^2.2.30",
    "@types/moment": "^2.13.0",
    "@types/moment-timezone": "^0.2.33",
    "@types/node": "^6.0.42",
    "angular-cli": "^1.0.0-beta.24",
    "bootstrap-sass": "^3.3.7",
    "codelyzer": "~0.0.26",
    "jasmine-core": "2.4.1",
    "jasmine-spec-reporter": "2.5.0",
    "karma": "1.2.0",
    "karma-chrome-launcher": "^2.0.0",
    "karma-cli": "^1.0.1",
    "karma-jasmine": "^1.0.2",
    "karma-remap-istanbul": "^0.2.1",
    "protractor": "4.0.9",
    "ts-loader": "^1.3.3",
    "ts-node": "1.2.1",
    "tslint": "4.2.0",
    "typescript": "2.0.2"
  }
}

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角cli.json

{
  "project": {
    "version": "1.0.0-beta.24",
    "name": "five-delivery-admin"
  },
  "apps": [
    {
      "root": "src",
      "outDir": "dist",
      "assets": ["assets"],
      "index": "index.html",
      "main": "main.ts",
      "test": "test.ts",
      "tsconfig": "tsconfig.json",
      "prefix": "app",
      "mobile": false,
      "styles": [
        "styles.scss",
        "../node_modules/hammerjs/hammer.min.js",
        "../node_modules/primeng/resources/themes/omega/theme.css",
        "../node_modules/primeng/resources/primeng.min.css",
        "../node_modules/font-awesome/css/font-awesome.min.css",
        "../node_modules/bootstrap/dist/css/bootstrap.min.css",
        "../node_modules/quill/dist/quill.core.css",
        "../node_modules/quill/dist/quill.snow.css",
        "../node_modules/quill/dist/quill.bubble.css"
      ],
      "scripts": [
        "../node_modules/quill/dist/quill.min.js",
        "../node_modules/hammerjs/hammer.min.js"
      ],
      "environments": {
        "source": "environments/environment.ts",
        "dev": "environments/environment.ts",
        "prod": "environments/environment.prod.ts"
      }
    }
  ],
  "addons": [],
  "packages": [],
  "e2e": {
    "protractor": {
      "config": "./protractor.conf.js"
    }
  },
  "test": {
    "karma": {
      "config": "./karma.conf.js"
    }
  },
  "defaults": {
    "styleExt": "scss",
    "prefixInterfaces": false
  }
}

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tsconfig.json

{
  "compilerOptions": {
    "declaration": false,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "allowSyntheticDefaultImports": true,
    "lib": ["es6", "dom"],
    "mapRoot": "./",
    "module": "es6",
    "moduleResolution": "node",
    "outDir": "../dist/out-tsc",
    "sourceMap": true,
    "target": "es5",
    "typeRoots": [
      "../node_modules/@types"
    ]
  }
}

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Answer 1

小智 90

所以我只是花了很多时间搞清楚这一点,但我做到了.

这也发生在我更新后,但它与此无关.

它绝对来自对具有空值的变量的引用,并且它很可能是图像src属性.至少它对我来说,我在我的应用程序中使用来自服务器的值,而imgsrc是导致这一点的唯一因素,这是有道理的.

我有类似的东西:

<img [src]="myData?.imageUrl">

我认为?安全操作符会确保我没有得到null错误,它通常会这样做,但是当你绑定到一个src属性时,浏览器会抛出一个错误,而不是编译器.由于安全操作符,编译器允许您将null绑定到它,但由于src是引用URL,浏览器仍在查找该URL,并且控制台因为无法找到URL而引发错误relative/app/path/null

我发现解决这个问题的两种方法:

使用ngIf :( <img *ngIf="myData" [src]="myData.imageUrl"/>如果没有数据,整个图像及其src属性永远不会被加载,完全避免了这个问题)
使用插值:( <img src="{{ myData?.imageUrl }}"/>注意在这个解决方案中你仍然需要安全操作符,因为编译器会抛出一个错误,否则,正如预期的那样,但是现在如果值为null,那么src=""而不是null,这是有效的HTML并且不会抛出引用错误)

希望这可以帮助!