将查询选择器结果转换为 vue 组件 <script lang="ts"> 代码中的 HTMLElement 时出现编译错误

Question

我基于 Vuejs 的项目中的一个组件具有以下 mounted 方法

mounted() {
  try {
    let x = 'abc';
    console.log(x);
    let body = <HTMLElement> document.querySelector("body");
  } catch (e) {
    console.log(e);
  }
}

编译（即 vue-cli-service lint file_path）因错误而失败

Parsing error: Unexpected token, expected "}"
console.log(e);
......................^

我的 eslintrc.js 看起来像这样（使用 babel-eslint 作为解析器）

module.exports = {
  root: true,
  env: {
    node: true,
  },
  extends: [
    'plugin:vue/essential',
  ],
  rules: {
    quotes: ['error', 'single']
  },
  parserOptions: {
    parser: 'babel-eslint',
  }
};

package.json 具有以下依赖项

"dependencies": {
    "@amcharts/amcharts4": "^4.6.1",
    "@sentry/browser": "^5.17.0",
    "@sentry/integrations": "^5.17.0",
    "@types/node": "^10.12.9",
    "@vue/cli-plugin-eslint": "^3.0.0-rc.3",
    "@vue/cli-plugin-typescript": "^3.0.0-rc.3",
    "@vue/cli-plugin-unit-mocha": "^3.0.0-rc.3",
    "@vue/cli-service": "3.9.3",
    "axios": "^0.15.3",
    "element-ui": "^2.8.2",
    "har-validator": "^5.1.3",
    "less-loader": "^4.1.0",
    "lodash": "^4.17.2",
    "moment": "^2.20.1",
    "typescript": "^3.0.1",
    "vee-validate": "^2.1.0-beta.7",
    "vue": "^2.5.16",
    "vue-authenticate": "^1.4.1",
    "vue-class-component": "^6.0.0",
    "vue-debounce": "^2.0.0",
    "vue-froala-wysiwyg": "^2.9.1",
    "vue-property-decorator": "^6.0.0",
    "vue-router": "^3.0.1",
    "vue-typeahead": "^2.3.0",
    "vuedraggable": "^2.21.0",
    "vuescroll": "^4.16.1",
    "vuetify": "1.1.0",
    "vuex": "^3.0.1",
    "vuex-router-sync": "^3.0.0",
    "vuex-saga": "^0.1.3"
  },
  "devDependencies": {
    "@types/chai": "^4.1.0",
    "@types/jest": "^23.3.10",
    "@types/mocha": "^2.2.46",
    "@types/webpack-env": "^1.15.2",
    "@vue/eslint-config-typescript": "^3.0.0-rc.3",
    "@vue/test-utils": "^1.1.0",
    "babel-core": "^6.26.0",
    "babel-jest": "^22.1.0",
    "babel-loader": "^7.1.2",
    "babel-polyfill": "^6.26.0",
    "babel-preset-env": "^1.6.1",
    "babel-preset-es2015": "^6.24.1",
    "babel-preset-stage-2": "^6.24.1",
    "babel-preset-stage-3": "^6.24.1",
    "chai": "^4.1.2",
    "dotenv": "^6.0.0",
    "faker": "^4.1.0",
    "file-system": "^2.2.2",
    "flush-promises": "^1.0.2",
    "jasmine-core": "^3.3.0",
    "jest": "^22.1.4",
    "jest-vue": "^0.8.2",
    "jquery": "^3.5.1",
    "less": "~3.9.0",
    "lint-staged": "^6.0.0",
    "regenerator-runtime": "^0.11.1",
    "ts-jest": "^23.0.1",
    "vue-jest": "^3.0.2",
    "vue-router": "^3.0.1",
    "vue-template-compiler": "^2.5.16"
  }

是什么导致了这个问题？顺便说一句，运行 eslint file_path 给出了同样的错误。

Answer 1

根据Typescript Documentation,

...when using TypeScript with JSX, only as-style assertions are allowed.

（意思是尖括号式断言是不允许的）。

尽管在 Vue 中很少使用 JSX，但 Vue 是 JSX compatible。这意味着您必须将类型断言限制为 as-style。换句话说，替换

let body = <HTMLElement> document.querySelector("body");

与

const body = document.querySelector("body") as HTMLElement;

或

const body: HTMLElement = document.querySelector("body");

注意：将 let 替换为 const 与所提问题无关，但如果您从未重新分配给 body，则应使用 const.

将查询选择器结果转换为 vue 组件 <script lang="ts"> 代码中的 HTMLElement 时出现编译错误

Compilation error on casting query selector result to HTMLElement inside a vue component's <script lang="ts"> code

type-assertion

typescript

vue.js

vue-cli

babel-eslint