Loops and Comprehensions

for_loop.coffee

#1) 
for name in ["Roger", "Roderick", "Brian"]
  alert "Release #{name}"

#2) if you need the current iteration index
for name, i in ["Roger the pickpocket", "Roderick the robber"]
  alert "#{i} - Release #{name}"

#3) iterate on one line using the postfix form
release prisoner for prisoner in ["Roger", "Roderick", "Brian"]

#4) using comprehensions to filter items
prisoners = ["Roger", "Roderick", "Brian"]
release prisoner for prisoner in prisoners when prisoner[0] is "R" 

#5) using comprehensions to iterate over properties of objects, use "of" instead of "in"
names = sam: seaborn, donna: moss
alert "#{first} #{last}" for first, last of names

for_loop.js

//1)
var name, _i, _len, _ref;
_ref = ["Roger", "Roderick", "Brian"];
for (_i = 0, _len = _ref.length; _i < _len; _i++) {
  name = _ref[_i];
  alert("Release " + name);
}

//2) if you need the current iteration index
var i, name, _len, _ref;
_ref = ["Roger the pickpocket", "Roderick the robber"];
for (i = 0, _len = _ref.length; i < _len; i++) {
  name = _ref[i];
  alert("" + i + " - Release " + name);
}

//3) iterate on one line using the postfix form
var prisoner, _i, _len, _ref;
_ref = ["Roger", "Roderick", "Brian"];
for (_i = 0, _len = _ref.length; _i < _len; _i++) {
  prisoner = _ref[_i];
  release(prisoner);
}

#4) using comprehensions to filter items
var prisoner, prisoners, _i, _len;
prisoners = ["Roger", "Roderick", "Brian"];
for (_i = 0, _len = prisoners.length; _i < _len; _i++) {
  prisoner = prisoners[_i];
  if (prisoner[0] === "R") {
    release(prisoner);
  }
}

#5) using comprehensions to iterate over properties of objects, use "of" instead of "in"
var first, last, names;
names = {
  sam: seaborn,
  donna: moss
};
for (first in names) {
  last = names[first];
  alert("" + first + " " + last);
}

while_loop.coffee

num = 6
minstrel = while num -= 1
  num + " Brave Sir Robin ran away"

while_loop.js

var minstrel, num;
num = 6;
minstrel = (function() {
  var _results;
  _results = [];
  while (num -= 1) {
    _results.push(num + " Brave Sir Robin ran away");
  }
  return _results;
})();