node.js - Node.js 的按键因数字而崩溃

Question

我对 Node.js 还很陌生，在处理一些示例时遇到了按键问题

这是我的代码:

'use strict';

var keypress = require('keypress');

// Make `process.stdin` begin emitting "keypress" events
keypress(process.stdin);

// Listening for the "keypress" event
process.stdin.on('keypress', function (ch, key) {
    if (key.name == 'e') {
        console.log('Emergency landing!');
    };  

    if (key.name == 'l') {
        console.log('Landing...');
    }

    if (key.name == 'x') {
        console.log('Goodbye!');
        process.exit();
    }
});

process.stdin.setRawMode(true);
process.stdin.resume();

如果我按字母，这会起作用，但如果按数字和其他字符，则会崩溃。

/Users/napolux/rollingspider/rs-1.js:16
    if (key.name == 'e') {
           ^

TypeError: Cannot read property 'name' of undefined
    at ReadStream.<anonymous> (/Users/napolux/rollingspider/rs-1.js:16:9)
    at emitTwo (events.js:87:13)
    at ReadStream.emit (events.js:172:7)
    at emitKey (/Users/napolux/rollingspider/node_modules/keypress/index.js:406:12)
    at ReadStream.onData (/Users/napolux/rollingspider/node_modules/keypress/index.js:48:14)
    at emitOne (events.js:77:13)
    at ReadStream.emit (events.js:169:7)
    at readableAddChunk (_stream_readable.js:146:16)
    at ReadStream.Readable.push (_stream_readable.js:110:10)
    at TTY.onread (net.js:523:20)

为什么会出现这个错误？

如何只允许某些字符或至少不崩溃？

Answer 1

读取字符的正确方法是

process.stdin.on('readable', function() {
  var chunk = process.stdin.read();
    if (chunk !== null) {
      process.stdout.write('data: ' + chunk);
    }
});

来自Nodejs.org

发生错误的原因是键可能“未定义”并且不包含属性名称。