Uncaught SyntaxError: Unexpected token {

Question

我正在尝试编写一个 chai 测试，我所做的只是流式传输一些音频并得到一个简单的响应：{}，出于某种原因我收到此错误 Uncaught SyntaxError: Unexpected token {每当我将我的 fs 流通过管道传输到 req 时，如果我移除管道并且我没有该流，则测试工作正常。

服务器代码：

router.post('/', function (clientRequest, clientResponse) {
    clientRequest.on('end', function () {//when done streaming audio
        console.log('im at the end>>>>>');
        clientResponse.setHeader('Content-Type', 'application/json'); //I've tried removing that: same result
        clientResponse.json({});
        clientResponse.end(); //I've tried removing that: same result
    }); //end clientRequest.on('end',)
});

测试代码：

var app = require('./app');

describe('server', function() {
    this.timeout(10000);
    it('should WORK!!!"', function (done){
        var req = chai.request(app).post('/speech');

        var readStream = fs.createReadStream('./test.wav');
        readStream.on('end',function(){
            console.log("readStream end>>>>>>>>>>>>>>>>>>>>>>");
            req.end(function (err, res) {
                console.log("req.end callback>>>>>>>>>>>>>>>");
                done();
            });
        });
        readStream.pipe(req);
    });
});

错误：

Uncaught SyntaxError: Unexpected token {
     at Object.parse (native)
     at _stream_readable.js:908:16

Answer 1

您可以尝试替换此命令

clientResponse.json({});

和

clientResponse.send({});

Answer 2

错误分析

一般的代码实际上是有效的，问题出在超级代理内部的某个地方。

实际上问题实际上缺少一些细节，所以我不得不猜测缺少的部分，比如 chai.request(app) 是使用 chai-http, which in turn uses superagent 执行 http 请求完成的。

问题似乎出在超级代理内部的某处，我能够通过更多信息重现您的错误（不确定为什么我得到更长的跟踪）：

Uncaught SyntaxError: Unexpected token {                                                                                                                      
 at Object.parse (native)                                                                                                                                     
 at IncomingMessage.<anonymous> (/project/path/node_modules/chai-http/node_modules/superagent/lib/node/parsers/json.js:9:2
 at IncomingMessage.EventEmitter.emit (events.js:117:20)                                                                                                      
 at _stream_readable.js:920:16                                                                                                                                
 at process._tickCallback (node.js:415:13) 

而且我能够检查 JSON 解析是否尝试解析双重响应。就像如果服务器响应 {}，解析器有 {}{}，或者如果服务器响应 {"a":"b"}，解析器有 {"a":"b"}{"a":"b"}。 您可以在 this line 之前插入 console.log(res.text) 自己检查（本地此文件在 node_modules/chai-http/node_modules/superagent 下）。

此外，如果我将 readStream.pipe(req); 移动到 var readStream 的行上方：

var readStream = fs.createReadStream('./test.wav');
readStream.pipe(req);
readStream.on('end',function(){
    ...

然后测试通过，但是输出'double callback!'——也是printed by superagent，确认有问题。

修复

没有chai-http和superagent做同样的事情并不复杂。

首先是server-side代码。它有点改变 - 而不是 clientRequest.on('end', ... 我将它通过管道传输到写入流。这样我也可以检查文件是否实际传输：

var express = require('express');
var fs = require('fs');

var app = express();

module.exports = app;

app.post('/speech', function (clientRequest, clientResponse) {
    console.log('speech');
    var writeStream = fs.createWriteStream('./test_out.wav');
    //for me on('end'... doesn't work (it infinitely waits for event
    //probably because the file is small and it finishes before we
    //get here
    clientRequest.pipe(writeStream).on('finish', function() {
        console.log('im at the end>>>>>');
        clientResponse.json({'a':'b'});
    });
});

app.listen(3000, function() {
  console.log("App started");
});

测试：

var fs = require('fs');
var chai = require('chai');
var http = require('http');

// Require our application and create a server for it
var app = require('./unexpected');
var server = http.createServer(app);
server.listen(0);
var addr = server.address();

describe('server', function() {
    this.timeout(10000);
    it('should WORK!!!"', function (done){
        // setup read stream
        var readStream = fs.createReadStream('./test.wav');
        readStream.on('end',function(){
            console.log("readStream end>>>>>>>>>>>>>>>>>>>>>>");
        });
        // setup the request
        var request = http.request({
            'host': 'localhost',
            'port': addr.port,
            'path': '/speech',
            'method': 'POST'
        });
        // now pipe the read stream to the request
        readStream.pipe(request).on('finish', function() {
            console.log("pipe end>>>>>>>>>>>>>>>>>>>>>>");
        });
        // get the response and finish when we get all the response data
        request.on('response', function(response) {
            console.log("request end>>>>>>>>>>>>>>>>>>>>>>");
            response.on('data', function(data) {
                console.log('response data: ' + data);
            });
            response.on('end', function(data) {
                console.log('done!');
                done();
            });
        });
    });
});

我认为代码应该是self-explanatory，我只是使用标准节点http module来完成这项工作。