标识符'_toConsumableArray'已被声明

Question

启动Redux应用程序时遇到此类问题：

./node_modules/draftjs-md-converter/dist/index.js
Syntax error: /Users/vlasenkona/Desktop/gris-seqr2/ui/node_modules/draftjs-md-converter/dist/index.js: Identifier '_toConsumableArray' has already been declared (196:9)

  194 | var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
  195 | 
> 196 | function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) { arr2[i] = arr[i]; } return arr2; } else { return Array.from(arr); } }
      |          ^
  197 | 
  198 | var parse = require('@textlint/markdown-to-ast').parse;
  199 | 
    at parser.next (<anonymous>)

启动脚本如下：

'use strict';

// Do this as the first thing so that any code reading it knows the right env.
process.env.BABEL_ENV = 'development';
process.env.NODE_ENV = 'development';

// Makes the script crash on unhandled rejections instead of silently
// ignoring them. In the future, promise rejections that are not handled will
// terminate the Node.js process with a non-zero exit code.
process.on('unhandledRejection', err => {
  throw err;
});

// Ensure environment variables are read.
require('../config/env');

const fs = require('fs');
const chalk = require('chalk');
const webpack = require('webpack');
const WebpackDevServer = require('webpack-dev-server');
const clearConsole = require('react-dev-utils/clearConsole');
const {
  choosePort,
  createCompiler,
  prepareProxy,
  prepareUrls,
} = require('react-dev-utils/WebpackDevServerUtils');
const openBrowser = require('react-dev-utils/openBrowser');
const paths = require('../config/paths');
const config = require('../config/webpack.config.dev');
const createDevServerConfig = require('../config/webpackDevServer.config');

const useYarn = fs.existsSync(paths.yarnLockFile);
const isInteractive = process.stdout.isTTY;

// Tools like Cloud9 rely on this.
const DEFAULT_PORT = parseInt(process.env.PORT, 10) || 3000;
const HOST = process.env.HOST || '0.0.0.0';

// We attempt to use the default port but if it is busy, we offer the user to
// run on a different port. `detect()` Promise resolves to the next free port.
choosePort(HOST, DEFAULT_PORT)
  .then(port => {
    if (port == null) {
      // We have not found a port.
      return;
    }
    const protocol = process.env.HTTPS === 'true' ? 'https' : 'http';
    const appName = require(paths.appPackageJson).name;
    const urls = prepareUrls(protocol, HOST, port);
    // Create a webpack compiler that is configured with custom messages.
    const compiler = createCompiler(webpack, config, appName, urls, useYarn);
    // Load proxy config
    const proxySetting = require(paths.appPackageJson).proxy;
    const proxyConfig = prepareProxy(proxySetting, paths.appPublic);
    // Serve webpack assets generated by the compiler over a web sever.
    const serverConfig = createDevServerConfig(
      proxyConfig,
      urls.lanUrlForConfig
    );
    const devServer = new WebpackDevServer(compiler, serverConfig);
    // Launch WebpackDevServer.
    devServer.listen(port, HOST, err => {
      if (err) {
        return console.log(err);
      }
      if (isInteractive) {
        clearConsole();
      }
      console.log(chalk.cyan('Starting the development server...\n'));
      openBrowser(urls.localUrlForBrowser);
    });

    ['SIGINT', 'SIGTERM'].forEach(function(sig) {
      process.on(sig, function() {
        devServer.close();
        process.exit();
      });
    });
  })
  .catch(err => {
    if (err && err.message) {
      console.log(err.message);
    }
    process.exit(1);
  });

在我切换到babel7之前，应用程序的启动工作正常，可以在我的其他线程中找到其过程（和相关的配置文件：

Switching to babel 7 causes jest to show 'unexpected token'

我曾尝试将draftjs-md-converter更新到最新版本，但未能解决问题。我在此线程中找到：

Identifier already declared - Identifier 'userScore' has already been declared

可能会发生这种错误，因为该应用程序以某种方式启动了两次，但不确定为什么立即开始这样做。

Answer 1

可以在这里找到解决方案：

https://github.com/kadikraman/draftjs-md-converter/pull/56

这是因为Babel 7和draftjs-md-converter都定义了_ toConsumableArray函数。因此，拉取请求是在实际的github页面上用包裹构建的问题，而解决方案如下：

git clone https://github.com/kadikraman/draftjs-md-converter.git
cd draftjs-md-converter
git checkout origin/chore/use-parcel-for-bundling
npm i
npm run compile

将文件从dist文件夹复制到node_modules / draftjs-md-converter / dist /]之后，解决了该问题。