Underscore.js's 'once' re-implemented. Returns a function that can only be called one time. Repeated calls to the modified function will result in returning the value from the original call

gistfile1.txt

_.once = function(func) {
  var alreadyCalled = false,
    result;

  return function() {
    if(!alreadyCalled) {
      result = func.apply(this, arguments);
      alreadyCalled = true;
    }
      
    return result;
  };
};