Node.js readline:意外的令牌=>

Question

我正在学习node.js并需要readline用于项目.我直接从readline模块示例中获得以下代码.

const readline = require('readline');

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

rl.question('What do you think of Node.js? ', (answer) => {
  // TODO: Log the answer in a database
  console.log('Thank you for your valuable feedback:', answer);

  rl.close();
});

但是当我通过node try.js命令运行代码时 ,它会不断发出如下错误:

rl.question('What is your favorite food?', (answer) => {
                                                    ^^
SyntaxError: Unexpected token =>
    at exports.runInThisContext (vm.js:73:16)
    at Module._compile (module.js:443:25)
    at Object.Module._extensions..js (module.js:478:10)
    at Module.load (module.js:355:32)
    at Function.Module._load (module.js:310:12)
    at Function.Module.runMain (module.js:501:10)
    at startup (node.js:129:16)
    at node.js:814:3

Answer 1

Arrow函数是ECMAScript 6标准的新功能之一,仅在4.0.0版本中引入node.js(作为稳定特性).

您可以升级node.js版本或使用旧语法,如下所示:

rl.question('What do you think of Node.js? ', function(answer) {
  // TODO: Log the answer in a database
  console.log('Thank you for your valuable feedback:', answer);

  rl.close();
});

(请注意,这些语法之间还有一个区别:this变量的行为方式不同.对于此示例而言,它无关紧要,但在其他示例中也可能无关紧要.)