javascript 去除重复元素

var newArray = []; 
    var A = Array(1,2,2,2,2,2,2); 
var B = Array(1,2,2,2,2,2,2); 
    for(var i =0 ;i<A.length;i++){ 
        for(var b =0 ;i<B.length;b++){ 
            if(A[i]==B[b]){ 
                var dx=a.getIndexByValue(A[i]); 
                A.remove(dx); 
            } 
        } 
         
    } 
    Array.prototype.remove=function(dx)   
{   
    if(isNaN(dx)||dx>this.length){return false;}   
    for(var i=0,n=0;i<this.length;i++)   
    {   
        if(this[i]!=this[dx])   
        {   
            this[n++]=this[i]   
        }   
    }   
    this.length-=1   
}   
    

Array.prototype.getIndexByValue= function(value)   
{   
    var index = -1;   
    for (var i = 0; i < this.length; i++)   
    {   
        if (this[i] == value)   
        {   
            index = i;   
            break;   
        }   
    }   
    return index;   
}