Error: stream.push() after EOF - node.js

Question

Playing with node steams
This code reads from index.js and writes to indexCopy.js - kind of file copy.
Target file got created, but during execution exception is thrown:
node index.js
events.js:183
throw er; // Unhandled 'error' event
^
Error: stream.push() after EOF
at readableAddChunk (_stream_readable.js:240:30)
at MyStream.Readable.push (_stream_readable.js:208:10)
at ReadStream.f.on (C:\Node\index.js:16:28)
at emitOne (events.js:116:13)
at ReadStream.emit (events.js:211:7)
at addChunk (_stream_readable.js:263:12)
at readableAddChunk (_stream_readable.js:250:11)
at ReadStream.Readable.push (_stream_readable.js:208:10)
at fs.read (fs.js:2042:12)
at FSReqWrap.wrapper [as oncomplete] (fs.js:658:17)
C:\Node>
This is code:
var util = require('util');
var stream = require('stream');
var fs = require('fs');
var MyStream = function(){
stream.Readable.call(this)
}
util.inherits(MyStream,stream.Readable);
MyStream.prototype._read = function(d){
f = fs.createReadStream("index.js");
f.on('data',(d)=>{this.push(d)});
f.on('end',()=>{this.push(null)}); //when file finished need to close stream
}
var f = fs.createWriteStream("indexCopy.js")
var myStream = new MyStream()
myStream.pipe(f);
I tried to call this.push(null) in 'data' event, in that case even target file is not created and code fails with the exception.
I realize that copy file should be done easier with pipe() function - I am just experimenting/learning.
What is wrong with my approach?

Answer 1

You don't want the f = fs.createReadStream("index.js") line inside the _read method -- _read gets called repeatedly so you're creating multiple read streams. Put that in your constructor instead.
function MyStream () {
stream.Readable.call(this);
this.source = fs.createReadStream("index.js");
this.haveBound = false;
}
MyStream.prototype._read = function () {
if (this.haveBound) return; // Don't bind to events repeatedly
this.haveBound = true;
this.source.on("data", d => this.push(d));
this.source.on("end", () => this.push(null));
};
This is awkward though. Streams are meant to be pipe'ed.