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();
}