Sums up function arguments

sum-function-arguments.js

/**
 * Sums up all given arguments.
 * @param {...*} var_args Numbers or numbers alike to sum up. 
 *     Numbers will be added as is, numbers in strings (e.g. '123.45') 
 *     will be converted to numbers and added. NaNs are skipped.
 * @return {number} The sum of number arguments.
 */
function sum(var_args) {
  var args = [].slice.call(arguments);
  
  // If all arguments are numbers, it is not required to map
  // converting every arguments to a number in arguments array.
  return args.map(function(numberAlike) {
    return typeof numberAlike === 'number' ? 
        numberAlike : (parseFloat(numberAlike, 10) || 0);

  }).reduce(function(a, b) {
    return a + b;
    
  }, 0);
}