How can I write a generator in a JavaScript class?

Question

Usually, I write code like this:

//definition exports.getReply = function * (msg){     //...     return reply;  } //usage var msg = yield getReply ('hello'); 

but how can I write and use a generator in and out of an es6 class? I tried this:

class Reply{     *getReply (msg){         //...         return reply;      }      *otherFun(){         this.getReply();  //`this` seem to have no access to `getReply`     } } var Reply = new Reply(); Reply.getReply();   //out of class,how can I get access to `getReply`? 

I also tried:

 class Reply{       getReply(){          return function*(msg){             //...             return reply;          }       }     } 

All of these two methods seem to be wrong answers. So how can I write generator functions in a class correctly?

Answer 1

Edit: Add more examples.
Your class definition is (almost) correct.The error was in instantiation var Reply = new Reply();. This tries to redefine variable assigned to class name. Also generator function is expected to yield something. I elaborated a little OP code to show working example.

class Reply {    //added for test purpose    constructor(...args) {      this.args = args;    }    * getReply(msg) {        for (let arg in this.args) {          let reply = msg + this.args[arg];          //generator should yield something          yield reply;        }        //next call returns (yields) {done:true,value:undefined}    }    * otherFun() {        yield this.getReply('Nice to meet you '); //yields Generator object        yield this.getReply('See you '); //Yes, this can access         //next call yields {done:true, value:undefined}    }    * evenMore() {        yield* this.getReply('I miss you '); //yields generator result(s)        yield* this.getReply('I miss you even more ');    }  }  //now test what we have  const reply = new Reply('Peter', 'James', 'John');  //let and var here are interchangeable because of Global scope  var r = reply.getReply('Hello ');  var msg = r.next(); //{done:false,value:"..."}  while (!msg.done) {    console.log(msg.value);    msg = r.next();  }  var other = reply.otherFun();  var o = other.next(); //{done:false,value:Generator}  while (!o.done) {    let gen = o.value;    msg = gen.next();    while (!msg.done) {      console.log(msg.value);      msg = gen.next();    }    o = other.next();  }  var more = reply.evenMore();  msg = more.next();  while (!msg.done) {    console.log(msg.value);    msg = more.next();  }  //update of 1/12/2019  //more examples  for (let r of reply.getReply('for ')) {    console.log(r);  }  for (let r of reply.evenMore()) {    console.log(r);  }  //note that the following doesn't work because of lack of star (*) inside the generator function  for (let r of reply.otherFun()) {    console.log(r);  }

UPDATE 1/12/2019

As suggested by @BugBuddy for..of loop looks even nicer (But doesn't work in all cases). See updated lines in the snippet.