在Node.js中使用through2向流发送数据时额外的换行符

Question

我正在浏览nodesschool的流探险workshopper。我要写一个程序来对这个过程进行管道化。Stdin流到使用through2模块创建的流，然后将其管道到process.stdout。使用through2模块创建的流将把输入流字符转换为大写，并将其管道到process.stdout。下面是我的源代码:

var through = require('through2');
var write = function(buffer,encoding,next){
        var data = buffer.toString();
        this.push(data.toUpperCase() + 'n');
        next();
}
var end = function (done){
        done();
}
var stream = through(write,end);
process.stdin.pipe(stream).pipe(process.stdout);

问题是，每发送到流中的第8个字块之后，就会打印一个额外的换行符。下面是workshopper执行的验证的3个测试输出:

测试1:

TAP version 13
# (anonymous)
ok 1 stream-adventure verify YOURFILE.js
not ok 2 should be equal
  ---
    operator: equal
    expected:
      'METALKINDnKORVENnOSIRIANnTHE ERGONnTYTHONIANnLAND OF FICTION BEINGSnSIRIANnKRAALnTHE FLOODnJADONDANn'
    actual:
      'METALKINDnKORVENnOSIRIANnTHE ERGONnTYTHONIANnLAND OF FICTION BEINGSnSIRIANnKRAALnnTHE FLOODnnJADONDANnn'
  ...
ok 3 successful exit code
1..3
# tests 3
# pass  2
# fail  1
#########################################
###   YOUR SOLUTION IS NOT CORRECT!   ###
#########################################

测试2:

TAP version 13
# (anonymous)
ok 1 stream-adventure verify YOURFILE.js
not ok 2 should be equal
  ---
    operator: equal
    expected:
      'THE BEASTnANDROZANI TREEnGAZTAKnRAXACORICOFALLAPATORIANnMAYFLYnSTIGORAXnTHE TRICKSTERnMEGARAnMENTORnHAND OF OMEGAn'
    actual:
      'THE BEASTnANDROZANI TREEnGAZTAKnRAXACORICOFALLAPATORIANnMAYFLYnSTIGORAXnTHE TRICKSTERnMEGARAnMENTORnnHAND OF OMEGAnn'
  ...
ok 3 successful exit code
1..3
# tests 3
# pass  2
# fail  1
#########################################
###   YOUR SOLUTION IS NOT CORRECT!   ###
#########################################

测试3:

TAP version 13
# (anonymous)
ok 1 stream-adventure verify YOURFILE.js
not ok 2 should be equal
  ---
    operator: equal
    expected:
      'QETESHnPELUSHInLURMANnEVEnATRAXInFLESHKINDnDALEKnGEE-JEE FLYnHEADLESS MONKnTHE DESTROYERn'
    actual:
      'QETESHnPELUSHInLURMANnEVEnATRAXInFLESHKINDnDALEKnGEE-JEE FLYnnHEADLESS MONKnnTHE DESTROYERnn'
  ...
ok 3 successful exit code
1..3
# tests 3
# pass  2
# fail  1
#########################################
###   YOUR SOLUTION IS NOT CORRECT!   ###
#########################################

这个神秘的额外换行符的原因是什么?我如何修复它?

Answer 1

在代码的第4行添加额外的换行符。要解决这个问题，您可以将第4行更改为:

this.push(data.toUpperCase() + 'n');

:

this.push(data.toUpperCase());

并且当您在终端

中键入此命令时，stream-adventure课程将打印它们的参考解决方案。

stream-adventure solution 

Answer 2

不要添加'n'，它已经在流中了。我猜你得到的缓冲区不止一行，所以'n'是随机添加的。