ES6,必须在访问“this”和在派生类中定义常量之前调用super

关键是,对于我的特殊情况,这个常数是 new Map() ,施工期间将咨询结果:

class Cmd0 {
  constructor(name, arg1, arg2 = null) {
    this.name = name;
    this.arg1 = arg1;
    this.arg2 = arg2;
  }
. . .
}

class Cmd extends Cmd0 {
  constructor(name, arg1, arg2 = null) {
    myMap =  Somehow.getMyMap() // defined in sub-classes
    if (!myMap.has(name)) { super(null, null, null); return } // fail the constructor
    super(name, arg1, arg2)
  }
}

class SubCmd1 extends Cmd {

  Usage() {
    if (this.name) return null
    else return "cmd sub1 bla bla bla"
  }
}

class SubCmd2 extends Cmd {

  Usage() {
    if (this.name) return null
    else return "cmd sub2 bla bla bla"
  }
}

SubCmd1 SubCmd2 getMyMap() this 可以访问。

这个

getMyMap() {
  return new Map()
    .set("name1", arg11, arg12)
    .set("name2", arg21, arg22)
}

有没有可能以某种方式使它起作用? https://jsbin.com/xubijosuro/edit?js,console,output

注:以下是我如何使用 亚CMD2 等:

const cli = new CliCaseA(name, argsObj) 
const usage = cli.Usage() 
if (usage) { console.log(`Usage:\n\n${usage}`) process.exit() }