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Const声明需要初始化值

typescript javascript

1

Robert Hovhannisyan · 技术社区 · 4 年前

我想将TypeScript添加到我的项目中,向数组中添加类型时出现以下错误:

SyntaxError:
my/path/of/file:
Const declarations require an initialization value (2:28)

  1 | //keycodes of restricted characters for all our amount inputs    
  2 | export const restrictedChars: number[] = [ 43, 45, 69, 107, 109, 187, 188, 189, 190 ];

代码如下:

//keycodes of restricted characters for all our amount inputs
export const restrictedChars: number[] = [ 43, 45, 69, 107, 109, 187, 188, 189, 190 ];

我试图声明数组,然后导出,但没有成功。此外,我还尝试为该数组创建一个接口,如一些解决此类问题的解决方案中所述,但没有太大帮助。

const path = require("path");
const webpack = require("webpack");

module.exports = {
  entry: "./src/index.tsx",
  mode: "development",
  module: {
    rules: [
      {
        test: /\.(js|jsx|ts|tsx)$/,
        exclude: /(node_modules|bower_components)/,
        loader: "babel-loader",
        options: { presets: ["@babel/env"] }
      },
      {
        test: /\.css$/,
        use: ["style-loader", "css-loader"]
      }
    ]
  },
  resolve: { extensions: ["*", ".js", ".jsx", ".ts", ".tsx"] },
  output: {
    path: path.resolve(__dirname, "dist/"),
    publicPath: "/dist/",
    filename: "bundle.js"
  },
  devServer: {
    contentBase: path.join(__dirname, "public/"),
    port: 3000,
    publicPath: "http://localhost:3000/dist/",
    historyApiFallback: true,
    hot: true
  },
  plugins: [new webpack.HotModuleReplacementPlugin()]
};

包.json

{
  "name": "WhatToCook",
  "version": "1.0.0",
  "description": "",
  "main": "./src/index.tsx",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "webpack-dev-server --mode development --open --hot"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@babel/cli": "^7.12.13",
    "@babel/core": "^7.12.13",
    "@babel/plugin-proposal-class-properties": "^7.12.13",
    "@babel/preset-env": "^7.12.13",
    "@babel/preset-react": "^7.12.13",
    "@types/react-dom": "^17.0.3",
    "@types/react-redux": "^7.1.16",
    "@types/react-router-dom": "^5.1.7",
    "babel-loader": "^8.2.2",
    "css-loader": "^1.0.1",
    "style-loader": "^0.23.1",
    "webpack": "^4.46.0",
    "webpack-cli": "^3.3.12",
    "webpack-dev-server": "^3.11.2"
  },
  "dependencies": {
    "lodash": "^4.17.20",
    "react": "^17.0.1",
    "react-addons-update": "^15.6.3",
    "react-dom": "^17.0.1",
    "react-hot-loader": "^4.13.0",
    "react-jss": "^10.5.1",
    "react-redux": "^7.2.2",
    "react-router-dom": "^5.2.0",
    "redux": "^4.0.5",
    "redux-devtools-extension": "^2.13.8",
    "redux-thunk": "^2.3.0"
  }
}

2 回复 | 直到 4 年前

1

2

Oleksandr K 4 年前

尝试在webpack配置中将ts loader放在js规则之前

      {
        test: /\.(ts|tsx)$/,
        loader: 'ts-loader',
        // include: [path.resolve(__dirname, 'yourAppPath')],
        exclude: [/node_modules/, /bower_components/],
      },
      {
        test: /\.(js|jsx)$/,
...

2

1

T.J. Crowder 4 年前

听起来好像这个代码没有被TypeScript处理。如果JavaScript引擎直接处理它,就会出现这样的错误:

/* export */ const restrictedChars: number[] = [ 43, 45, 69, 107, 109, 187, 188, 189, 190 ];

确保这是在一个 .ts .tsx 文件,不是 .js 或 .jsx 文件,并且您的项目设置为让TypeScript编译将文件转换为JavaScript。

restrictedChars . TypeScript将正确推断类型 number[] 来自初始值设定项。(TypeScript在推断类型方面非常聪明。)