var object  = {
    a : 50,
    b: 60
}
var x = JSON.parse(JSON.stringify(object));
console.log(x);

// timer methods from web API 

setTimeout(function(){
    console.log('after 5 sec');
}, 5000);

var xhr = new XMLHttpRequest();
xhr.onreadystatechange =  function(){
    if(this.readyState == 4){
        clearTimeout(timeout);
    }
}
var timeout = setTimeout (function(){
     xhr.abort(); 
}, 2000);

xhr.open('GET', url, true);
xhr.send();
 
//----------------------------------------------//

function hello(a,b) {
    return a+b;
}

function add(a){
    return function(b){
        return function(c){
              return a+b+c;
        }
    }
}
add(4)(5)(8);

var x = add(4);
var y = x(5);
var z = y(8);

/************************************************* */

var keywords = ["do","if","else","for" ,"switch"];

keywords
    .filter( i =>  i.length > 3 )
    .map(    i =>  i.concat('Hi') )
    .sort( (a,b) => a < b ? -1 : 1);

/************************************************ */

class ChainAble {
  firstMethod() {
    console.log('This is the First Method');
    return this;
  }
  
  secondMethod() {
    console.log('This is the Second Method');
    return this;
  }
  
  thirdMethod() {
    console.log('This is the Third Method');
    return this;
  }
}

const chainableInstance = new Chainable()
chainableInstance
  .firstMethod()
  .secondMethod()
  .thirdMethod();
  
  /**************************************************** */