prototype/src/array.js

var $A = Array.from = function(iterable) {
  if (!iterable) return [];
  if (iterable.toArray) {
    return iterable.toArray();
  } else {
    var results = [];
    for (var i = 0, length = iterable.length; i < length; i++)
      results.push(iterable[i]);
    return results;
  }
}

Object.extend(Array.prototype, Enumerable);

if (!Array.prototype._reverse)
  Array.prototype._reverse = Array.prototype.reverse;

Object.extend(Array.prototype, {
  _each: function(iterator) {
    for (var i = 0, length = this.length; i < length; i++)
      iterator(this[i]);
  },
  
  clear: function() {
    this.length = 0;
    return this;
  },
  
  first: function() {
    return this[0];
  },
  
  last: function() {
    return this[this.length - 1];
  },
  
  compact: function() {
    return this.select(function(value) {
      return value != null;
    });
  },
  
  flatten: function() {
    return this.inject([], function(array, value) {
      return array.concat(value && value.constructor == Array ?
        value.flatten() : [value]);
    });
  },
  
  without: function() {
    var values = $A(arguments);
    return this.select(function(value) {
      return !values.include(value);
    });
  },
  
  indexOf: function(object) {
    for (var i = 0, length = this.length; i < length; i++)
      if (this[i] == object) return i;
    return -1;
  },
  
  reverse: function(inline) {
    return (inline !== false ? this : this.toArray())._reverse();
  },
  
  reduce: function() {
    return this.length > 1 ? this : this[0];
  },
  
  uniq: function(sorted) {
    return this.inject([], function(array, value, index) {
      if (0 == index || (sorted ? array.last() != value : !array.include(value)))
        array.push(value);
      return array;
    });
  },
  
  clone: function() {
    return [].concat(this);
  },
  
  size: function() {
    return this.length;
  },
  
  inspect: function() {
    return '[' + this.map(Object.inspect).join(', ') + ']';
  }
});

Array.prototype.toArray = Array.prototype.clone;

function $w(string){
  string = string.strip();
  return string ? string.split(/\s+/) : [];
}

if(window.opera){
  Array.prototype.concat = function(){
    var array = [];
    for(var i = 0, length = this.length; i < length; i++) array.push(this[i]);
    for(var i = 0, length = arguments.length; i < length; i++) {
      if(arguments[i].constructor == Array) {
        for(var j = 0, arrayLength = arguments[i].length; j < arrayLength; j++) 
          array.push(arguments[i][j]);
      } else { 
        array.push(arguments[i]);
      }
    }
    return array;
  }
}