TypeError: Buffer.allocUnsafe is not a function

1、错误描述

> Buffer.allocUnsafe(10);
TypeError: Buffer.allocUnsafe is not a function
    at repl:1:8
    at REPLServer.defaultEval (repl.js:262:27)
    at bound (domain.js:287:14)
    at REPLServer.runBound [as eval] (domain.js:300:12)
    at REPLServer.<anonymous> (repl.js:431:12)
    at emitOne (events.js:82:20)
    at REPLServer.emit (events.js:169:7)
    at REPLServer.Interface._onLine (readline.js:211:10)
    at REPLServer.Interface._line (readline.js:550:8)
    at REPLServer.Interface._ttyWrite (readline.js:827:14)
> Buffer.allocUnsafe(5);
TypeError: Buffer.allocUnsafe is not a function
    at repl:1:8
    at REPLServer.defaultEval (repl.js:262:27)
    at bound (domain.js:287:14)
    at REPLServer.runBound [as eval] (domain.js:300:12)
    at REPLServer.<anonymous> (repl.js:431:12)
    at emitOne (events.js:82:20)
    at REPLServer.emit (events.js:169:7)
    at REPLServer.Interface._onLine (readline.js:211:10)
    at REPLServer.Interface._line (readline.js:550:8)
    at REPLServer.Interface._ttyWrite (readline.js:827:14)

2、错误原因

由官网上的实例，尝试着做了下，发现报这个错误

3、解决办法