console-1598082325813.log

function iamAsync(success,fail){
var a = 10;
setTimeout(function(){
console.log("I am After 5 Sec Going to Return ");
if(a>10){
success("I am the Result of Async"); // I am Calling the CallBack
}
else{
fail("Some Error Occur ");
}
//return "I am The Result of Async ";
//document.write('I will call after 5 sec ');
},5000);
}
undefined
function fail(err){
console.log(" I am Fail Error ",err);
}
undefined
function giveMeResult(result){
console.log(" I am the Result ",result);
}
undefined
iamAsync(giveMeResult,fail);
undefined
VM101:4 I am After 5 Sec Going to Return 
VM107:2  I am Fail Error  Some Error Occur 
function delData(){
var pr = new Promise(function(resolve, reject){
setTimeout(function(){
    let x = 10;
    let y = 20;
    console.log('I call after 5 sec ');
    resolve("I am the Data From Async "+(x+y));
},5000);
});

return pr;
}
undefined
var p = delData();
console.log('P is ',p);
p.then(function(data){
console.log('I Rec the Data ',data);
}).catch(function(err){
console.log('Error is ',err);
});
VM1030:2 P is  Promise {<pending>}
Promise {<pending>}
VM707:6 I call after 5 sec 
VM1030:4 I Rec the Data  I am the Data From Async 30
p;
Promise {<fulfilled>: "I am the Data From Async 30"}