js Array 数组方法扩展

//去重复
  Array.prototype.unique = function()
 {
    this .sort();
    var re=[ this [ 0 ]];
    for (var i = 1 ; i < this .length; i++)
    {
        if ( this [i] !== re[re.length- 1 ])
        {
            re.push( this [i]);
        }
    }
    return re;
 }

 //并集
 Array.prototype.union = function(a)
 {
   return this .concat(a).unique();

 }
 //差集
 Array.prototype.minus = function(a)
 {
    var result =[];
    var clone = this ;
      for (var i= 0 ; i < clone.length; i++)
      {
          var flag = true ;
          for (var j= 0 ; j < a.length; j++)
          {
            if (clone[i] == a[j])
            flag = false ;
          }
        if (flag)
        result.push(clone[i]);

      }

    return result.unique();

 }
// 交集
Array.prototype.intersect = function(b) {
    var result = [];
    var a = this ;
    for (var i = 0 ; i < b.length; i ++) {
        var temp = b[i];
        for (var j = 0 ; j < a.length; j ++) {
            if (temp === a[j]) {
                result.push(temp);
                break ;
            }
        }
    }
    return result.unique();
}