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我试图使用反应入门套件。

几个小时前，我能够在本地服务器上运行我的 html 代码。我通过“node server.js”启动服务器。但现在我无法运行我的应用程序。

每当我尝试运行它时，我都会显示这样的网页。我在运行“node server.js”时遇到这样的错误。

我知道这意味着端口 3000 已经在使用中，但是当我第一次启动它时它也不起作用。这一切都是几个小时前的工作。

服务器.js

var fs = require('fs');
var path = require('path');
var express = require('express');
var bodyParser = require('body-parser');
var app = express();

var COMMENTS_FILE = path.join(__dirname, 'comments.json');

app.set('port', (process.env.PORT || 3000));

app.use('/', express.static(path.join(__dirname, 'public')));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
  extended: true
}));

// Additional middleware which will set headers that we need on each request.
app.use(function(req, res, next) {
  // Set permissive CORS header - this allows this server to be used only as
  // an API server in conjunction with something like webpack-dev-server.
  res.setHeader('Access-Control-Allow-Origin', '*');

  // Disable caching so we'll always get the latest comments.
  res.setHeader('Cache-Control', 'no-cache');
  next();
});

app.get('/api/comments', function(req, res) {
  fs.readFile(COMMENTS_FILE, function(err, data) {
    if (err) {
      console.error(err);
      process.exit(1);
    }
    res.json(JSON.parse(data));
  });
});

app.post('/api/comments', function(req, res) {
  fs.readFile(COMMENTS_FILE, function(err, data) {
    if (err) {
      console.error(err);
      process.exit(1);
    }
    var comments = JSON.parse(data);
    // NOTE: In a real implementation, we would likely rely on a database   or
    // some other approach (e.g. UUIDs) to ensure a globally unique id.   We'll
    // treat Date.now() as unique-enough for our purposes.
    var newComment = {
      id: Date.now(),
      author: req.body.author,
      text: req.body.text,
    };
    comments.push(newComment);
    fs.writeFile(COMMENTS_FILE, JSON.stringify(comments, null, 4), function(err) {
      if (err) {
        console.error(err);
        process.exit(1);
      }
      res.json(comments);
    });
  });
});


app.listen(app.get('port'), function() {
  console.log('Server started: http://localhost:' + app.get('port') + '/');
});

这是hello.html

<!-- index.html -->
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8" />
  <title>React Tutorial</title>
  <script src="https://npmcdn.com/react@15.3.0/dist/react.js"></script>
  <script src="https://npmcdn.com/react-dom@15.3.0/dist/react-dom.js"></script>
  <script src="https://npmcdn.com/babel-core@5.8.38/browser.min.js"></script>
  <script src="https://npmcdn.com/jquery@3.1.0/dist/jquery.min.js"></script>
  <script src="https://npmcdn.com/remarkable@1.6.2/dist/remarkable.min.js"></script>
</head>
<body>
<div id="content"></div>

<script type="text/babel">
  // tutorial1.js
  var CommentBox = React.createClass({
    render: function() {
      return (
        <div className="commentBox">
          Hello, world! I am a CommentBox.
        </div>
      );
    }
  });
  ReactDOM.render(
    <CommentBox />,
    document.getElementById('content')
  );
  // To get started with this tutorial running your own code, simply remove
  // the script tag loading scripts/example.js and start writing code here.
</script>
</body>
</html>
4

1 回答 1

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检查您计算机上的进程，因为有一个使用端口 3000。

您需要在重新启动应用程序之前将其杀死，或更改服务器的端口（例如：app.set('port', (process.env.PORT || 3010));

于 2016-08-05T12:28:37.470 回答