Node.js 自定義流

var Readable = require("stream").Readable; 
var util = require("util"); 
/* www.o2fo.com */
function Counter() { 
    Readable.call(this); 
    this._max = 10; 
    this._index = 1; 
} 
util.inherits(Counter, Readable); 

Counter.prototype._read = function () { 
    var i = this._index++; 
    if (i > this._max)
        this.push(null);
    else { 
        var str = " " + i; 
        this.push(str);
    } 
}; 
// Usage, same as any other readable stream 
var counter = new Counter(); 
counter.pipe(process.stdout); 

var Writable = require("stream").Writable; 
var util = require("util"); 
/* www.o2fo.com */
function Logger() {
     Writable.call(this); 
} 
util.inherits(Logger, Writable); 

Logger.prototype._write = function (chunk) {
     console.log(chunk.toString()); 
}; 

// Usage, same as any other Writable stream 
var logger = new Logger(); 

var readStream = require("fs").createReadStream("log.txt"); 
readStream.pipe(logger);