task-prototype4.js

/*
1. add defer() to all function prototypes
2. should wait for n second, then invoke a function
3. (!) and return a function
function f() {
  console.log( a + b );
}
f.defer(1000)(1, 2); //after delay 1sec, 3
*/
Function.prototype.defer = function(ms) {
  return function() {
    var args = arguments;
    
    setTimeout(function() {
      this.apply(this, args);
    }.bind(this), ms);
  }.bind(this)
}

/*
in ES6

Function.prototype.defer = function(ms) {
  var self = this;
   
  return function() {
    setTimeout(() => {
      self.apply(this, arguments);
    }, ms);
  }
}
*/

function f(a, b) {
  console.log( a + b );
}

f.defer(1000)(1, 2);