flatten-array.js

/**
 * Resursively flattens an Array of depth n
 * 
 * @param aSrc Array to be flattened
 * @returns Array Single depth array
 */
var flatten = function(aSrc) {

  if (Array.isArray(aSrc) && aSrc.length > 0) { // Test that paramater is both array and non-zero length
    var head = aSrc[0],                         // Get first element from paramater
        tail = aSrc.slice(1);                   // Get the rest of array after first element

    return flatten(head).concat(flatten(tail)); // Continue flattening, start with first elem and add remainder
  } else {                                      // Parameter is not array, add to new array and return
    return [].concat(aSrc);
  }
};

// flatten([1,2,[3,[4]],5,[[[6]]]])