For Await Of Loop

    /**
     * for await(let val of obj) {
     *   use the asynchronous result
     * }
     */
    
    let thing = [
      new Promise(resolve => {
        setTimeout(resolve, 4000, "one");
      }),
      new Promise(resolve => {
        setTimeout(resolve, 1000, "two");
      }),
      new Promise(resolve => {
        setTimeout(resolve, 1000, "three");
      })
    ];
    //all 3 promises are being created as soon as the page runs
    //so we need different timeout delay values
    
    (async function() {
      for await (let res of thing) {
        console.log(res);
      }
    })();


    /**
     *  async iter
     * 
     */
    let myObj = {
      //add an asyncIterator method to my object
      [Symbol.asyncIterator]() {
        //which will return an object that contains a method called next()
        return {
          i: 0 /* my counter property */,
          next() {
            if (this.i < 3) {
              //return value from the next method must be an object
              //the object should contain a value and a done property
              return new Promise(resolve => {
                let obj = { value: this.i, done: false };
                this.i = this.i + 1;
                setTimeout(resolve, 1000, obj);
                //this timeout delay value is not set until next() is called by for await...of
              });
            }
            //once our counter value is 3 or more tell whoever called next that we are done
            return new Promise(resolve => {
              setTimeout(resolve, 3000, { done: true });
            });
          }
        };
      }
    };
    
    (async function() {
      for await (let num of myObj) {
        console.log(num);
      }
    })();