JS Master Class Homework

js-masterclass-homework-easy.js

// 1. Write a class to support the following code:
var thomas = new Person('Thomas');
var amy = new Person('Amy');

thomas.name // --> "Thomas"

// 2. Add a getName() method to all Person objects, that outputs
// the persons name.

thomas.getName() // --> "Thomas"

// 3. Write a statement that calls Thomas's getName function,
// but returns "Amy". (Don't change or redefine the getName 
// function in any way.)

// 4. Remove the getName() method from all Person objects.


function Person( name ){
	this.name = name;
};

Person.prototype = {
	getName: function(){
		return this.name;
	}
};

thomas.getName.call(amy);

delete Person.prototype.getName;

js-masterclass-homework-hard.js

// Part 1.
// Implement a function prototype extension that caches function results for
// the same input arguments of a function with one parameter.
//
// For example:
// Make sin(1) have the result of Math.sin(1), but use a cached value
// for future calls.
//
// Part 2.
// Use this new function to refactor the code example.
// Some good test numbers: 524287, 9369319, 2147483647 (all primes)
//
// In other words, if you have this code:
//
//  Function.prototype.cached = function(){
//    ? (what goes here?)
//  }
//  
//  // For the isPrime function
//  
//  var cachedIsPrime = isPrime.cached();
//  isPrime(11); // --> true (cache miss, calls original isPrime(1) function, stores return value in cache)
//  isPrime(11); // --> true (cache hit, directly returns value)
//  
//  // ..but it short work on anything that takes just one (numeric) argument:
//  
//  var cachedSin = Math.sin.cached();
//  
//  cachedSin(1); // --> 0.8414709848078965 (cache miss, calls original Math.sin(1) function, stores return value in cache)
//  cachedSin(1); // --> 0.8414709848078965 (cache hit, directly returns value)
Function.prototype.cached = function(){
	
	var origFunc = this
	  , cache = {};

	return function( arg ){

		if( cache[ arg ] === undefined )
			cache[ arg ] = origFunc( arg );

		return cache[ arg ];
	};

};

var isPrime = function( num ) { 
  var prime = num != 1;
  for ( var i = 2; i < num; i++ ) { 
    if ( num % i == 0 ) { 
      prime = false; 
      break; 
    } 
  } 
  
  return prime; 
}.cached();