简化的构造函数API

在简单的情况下，不通过继承来构建流，现在会有一些额外的好处。

这可以通过传递适当的方法作为构造选项来实现：

例子：

Readable

  1. var readable = new stream.Readable({
  2.     read: function (n) {
  3.         // sets this._read under the hood
  5.         // push data onto the read queue, passing null
  6.         // will signal the end of the stream (EOF)
  7.         this.push(chunk);
  8.     }
  9. });

Writable

  1. var writable = new stream.Writable({
  2.     write: function (chunk, encoding, next) {
  3.         // sets this._write under the hood
  5.         // An optional error can be passed as the first argument
  6.         next()
  7.     }
  8. });
  10. // or
  12. var writable = new stream.Writable({
  13.     writev: function (chunks, next) {
  14.         // sets this._writev under the hood
  16.         // An optional error can be passed as the first argument
  17.         next()
  18.     }
  19. });

Duplex

  1. var duplex = new stream.Duplex({
  2.     read: function (n) {
  3.         // sets this._read under the hood
  5.         // push data onto the read queue, passing null
  6.         // will signal the end of the stream (EOF)
  7.         this.push(chunk);
  8.     },
  9.     write: function (chunk, encoding, next) {
  10.         // sets this._write under the hood
  12.         // An optional error can be passed as the first argument
  13.         next()
  14.     }
  15. });
  17. // or
  19. var duplex = new stream.Duplex({
  20.     read: function (n) {
  21.         // sets this._read under the hood
  23.         // push data onto the read queue, passing null
  24.         // will signal the end of the stream (EOF)
  25.         this.push(chunk);
  26.     },
  27.     writev: function (chunks, next) {
  28.         // sets this._writev under the hood
  30.         // An optional error can be passed as the first argument
  31.         next()
  32.     }
  33. });

Transform

  1. var transform = new stream.Transform({
  2.     transform: function (chunk, encoding, next) {
  3.         // sets this._transform under the hood
  5.         // generate output as many times as needed
  6.         // this.push(chunk);
  8.         // call when the current chunk is consumed
  9.         next();
  10.     },
  11.     flush: function (done) {
  12.         // sets this._flush under the hood
  14.         // generate output as many times as needed
  15.         // this.push(chunk);
  17.         done();
  18.     }
  19. });