A sloppy example on JavaScript curry function

currying_example.js

/**
 * A sloppy example on JavaScript curry function
 *
 * @author Vladimir Ivic <[email protected]> 
 * @github http://github.com/mancmelou
 */

/**
 * Here we are, the curried function definition
 */ 
var add = function (a, b) {
  if (a === undefined && b === undefined) {
    // in case no args are passed return the function
    return add;
  } else if (b === undefined) {
    // if the last parameter is omitted, return a new 
    // function that will call the original function 
    return function (b) {
      return add(a, b);
    };
  } else {
    // all parameters here; good; perform
    return a + b; 
  }
};

/**
 * Some usage examples
 */ 

// example 1. immediate call 
add(3, 4) === 7;

// example 2. immediate call with the split parameters
add(3)(4) === 7;

// example 2. intermediate call. 
// call function when we know the first param, then do some other 
// processing and then call it again when the second param is known
var added_3 = add(3);
console.log("Doing something else...");
console.log("Doing something else...");
console.log("Ok, time to finish the add() operation...");
added_3(4) === 7;

// example 3. not a real world usage example though
add()()()()()()(3)(4) === 7;

add(3)()()()()()(4) === 7;