Winston: 类型错误：logger.child 不是函数

请告诉我们您的环境：

• _ winston版本？_
  
  
  
  • [ ] winston@2
  
  
  • [x] winston@3
  
  
• _ node -v输出：v10.15.0
• _操作系统？ 苹果系统
• _语？ ES5/6

问题是什么？

const winston = require('winston');

const logger = winston.createLogger({
  transports: [new winston.transports.Console()],
});
logger.info('logger ok.');

const childLogger = logger.child({ test: 'test value' });
childLogger.info('child logger ok');

你期望发生什么？

{"message":"logger ok.","level":"info"}
{"message":"child logger ok.","level":"info"}

其他信息

TypeError: logger.child is not a function
    at Object.<anonymous> (/Users/onlybalance/test/logger.js:12:28)
    at Module._compile (internal/modules/cjs/loader.js:689:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:700:10)
    at Module.load (internal/modules/cjs/loader.js:599:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:538:12)
    at Function.Module._load (internal/modules/cjs/loader.js:530:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:742:12)
    at startup (internal/bootstrap/node.js:283:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:743:3)