buffer缓冲区

buffer : 数据的缓冲区，也是一个类，不是模块

怎么创建buffer :

1. node 6.0 之前的方式

new Buffer();

2. 现在的创建方式

参数 ：内容的大小，单位是字节 b
let buffer = Buffer.alloc(10);
console.log(buffer);

buffer会把所有数据转换成二进制，然后以十六进制的方式展示出来

let buffer = Buffer.from("大家好");
console.log(buffer);
console.log(buffer.toString());

let buffer1 = Buffer.from([0xe5, 0xa4, 0xa7, 0xe5, 0xae]);
let buffer2 =  Buffer.from([0xb6, 0xe5, 0xa5, 0xbd]);

let newbuffer = Buffer.concat([buffer1,buffer2]);
console.log(newbuffer.toString());

// StringDecoder 固定名称
let { StringDecoder } = require("string_decoder");

let decoder = new StringDecoder();

let res1 = decoder.write(buffer1);
let res2 = decoder.write(buffer2);

console.log(res1 + res2);