split.js

// This is a string... (looks like a list but still a string)
var animalsString = "cow,dog,horse,moose,rooster";

// Turn the string into an array...
var animalsArray = animalsString.split(",");

// Now you can go about looping, like normal...
for (var i = 0; i < animalsArray.length; i++) {
  // animalsArray[i]
}