implementing for-of loop

for-of-loop.js

// implementation of "for of loop"
function forOf(iterable,callback){
	var iterator = iterable[Symbol.iterator]();
  	var result=iterator.next();
  	var index=0;
  	while(!result.done){
    	callback(result.value,index);
      	result=iterator.next();
      	index++;
    }
}

// custom Iterable object
class Users {
  constructor(users){
    this.users=users;
  }
  [Symbol.iterator](){
    var index=0;
    var len= this.users.length;
    var result=null;
    return {
    	next:()=>{
          result={value:this.users[index],done:!(index<len)}
          index++;
          return result;
        }
    }
  }
}

const names = ['John', 'Mary', 'Christine', 'Edward', 'James'];
const users = new Users(names);
forOf(users,(user)=>{
  console.log('using forOf :',user);
})

for (let user of users) {
  console.log('using for-of-loop : ',user);
}

console.log('using spread operator:', ...users)