anubhavsrivastava

function add(x){
  let sum = x;
  function resultFn(y){
   sum +=y;
   return resultFn;
  }
  resultFn.valueOf = function(){ return sum }; 
  return resultFn;
}

anubhavsrivastava

function add(x){
    return function (y){
        return x+y;
    }
}


//ES6 version using arrow functions
const add = x=> y=>x+y;