SOURCE

function doPromiseTask(){
    var promise=new Promise(function(resolve){
        setTimeout(function(){
            console.log("Timeout Finished and recolve promise 1");
            resolve();
        },3000);
    });
    return promise;
}
function doPromiseTask2(){
    var promise=new Promise(function(resolve){
        setTimeout(function(){
            console.log("Timeout Finished and recolve promise 2");
            resolve();
        },3000);
    });
    return promise;
}

async function callAwaitFunctions(){
    console.log("callPromise1Await Start");
    await this.doPromiseTask().then(function(res){
        console.log("Start calcutte after resove");
        // sleep(100);
        console.log("Start calcutte after resov--finished"+sum);
        this.doPromiseTask2().then(function(res){
            console.log("1235546");
        });
        // setTimeout(function(){
        //     console.log("callPromise1Await Finished");
        // },3000);
    });
     console.log("callPromise1Await End");
}
function sleep(delay) {
  var start = (new Date()).getTime();
  while ((new Date()).getTime() - start < delay) {
      console.log((new Date()).getTime() - start );

    continue;
  }
}
callAwaitFunctions();