Every, Some and Reduce

every.js

Array.prototype.every = function (fn) {
  return this.reduce(function (a, b){ return a && fn(b); }, true);
}

reduce.js

Array.prototype.reduce = function reduce(accumulator, start) {
  var curr, i;

  if (arguments.length == 1) {
    curr = this[0]; // Increase i to start searching the secondly defined element in the array
    i = 1; // start accumulating at the second element
  }
  else {
    curr = start;
    i = 0;
  }

  for (i = i || 0 ; i < this.length ; ++i) {
    curr = accumulator(curr, this[i]);
  }

  return curr;
};

somefilter.js

Array.prototype.some = function (fn) {
  return this.filter(fn).length > 0;
}

somereduce.js

Array.prototype.some = function (fn) {
  return this.reduce(function (a, b){ return a || fn(b); }, false);
}