step-example.js

// Allows for an array or an array like structure to be stepped through in the order specified
// after each iteration.
function step(array, callback, opt_stepValue, opt_startIndex) {
  opt_stepValue = ~~opt_stepValue || 1;
  var count = array.length;
  var i = (opt_startIndex == undefined || isNaN(~~opt_startIndex))
    ? opt_stepValue < 0
      ? count - 1
      : 0
    : opt_startIndex;
  i = (~~i % count + count) % count;
  for (var newStep, result = []; 0 <= i && i < array.length; i += opt_stepValue) {
    newStep = callback(array[i], i, array);
    result.push(array[i]);
    opt_stepValue = newStep != undefined ? ~~newStep || 0 : opt_stepValue;
  }
  return result;
}

// CODE BREAK \\
step([1,2,3,4,5,6,7,8,9], function(value, index, array) {
  if (index % 2 === 0) {
    array[index] = String.fromCharCode(value + 64);
  }
});

// CODE BREAK \\
step([1,2,3,4,5,6,7,8,9], function(value, index, array) {
  if (index % 2 === 0) {
    array[index] = String.fromCharCode(value + 64);
    return 2;
  }
});

// CODE BREAK \\
step([1,2,3,4,5,6,7,8,9], function(value, index, array) {
  if (index % 2 === 0) {
    array[index] = String.fromCharCode(value + 64);
  }
}, -2, -1);