Simple Promise implementation in Node

Promise.js

class Promise {

  constructor(fn) {
    this.thens = [];
    this.state = 'pending';
    this.value = undefined;
    fn(this.resolve.bind(this));
    return this;
  }

  resolve() {
    this.value = arguments[0];
    this.state = 'resolved';
    while(this.thens.length>0) {
      const f = this.thens.pop();
      f(this.value);
    }
  }

  then(fn) {
    if (this.state==='resolved') {
      //console.log('inside then');
      fn(this.value);
    } else {
      this.thens.push(()=>fn(this.value));
    }
    return this;
  }

}

//tests
const p = new Promise((resolve)=>{
  setTimeout(()=>{
    resolve(1);
  }, 100);
});

p.then((value)=>{
  console.log(value);
  p.then((value2)=>console.log(value2))
    .then(function(){
      console.log(arguments)
    });
});