JS数组复制,该怎么处理

var my_arr = new Array(1,2,3,3,4,5,6,6,7,8,9,10,11,11,10,11,12,13);
var p_v_copy = my_arr;
for(var l = 0; l < my_arr.length; l++){
    //初始重复判断变量
    var no_repeat = 1;
    
    //查找积是否不重复
    for(var m = 0; m < my_arr.length; m++){
        if(l == m){
            continue;
        }
        if(my_arr[l] == my_arr[m]){
            no_repeat = 0;
            break;
        }
    }
    
    //积不重复时，删除复制数组里面的此值对
    if(no_repeat){
        p_v_copy[l] = 'mark';
    }
}
document.write(my_arr + '<br />');
document.write(p_v_copy);
var a = 3;
var b = a;
document.write(a + '<br />');
document.write(b + '<br />');
b = 4;
document.write(a + '<br />');
document.write(b + '<br />');