为什么我的代码触发不了data事件，，其他都可以
var fs=require('fs');
var readStream=fs.createReadStream('stream_copy_logo.js');
var n=0
readStream
.on('data',function(chunk){
//触发了data事件
n++;
console.log('data emits');
console.log(Buffer.isBuffer(chunk))
//console.log(chunk.toString('utf8'));
//流的暂停
readStream.pause();
console.log('data pause');
//加一个3秒的延迟
setTimeout(function(){
console.log('data pause stop end')
readStream.resume()
},3000)
})
