javascript function arguments

i want to pass an array to a function and work on it,but i am afraid ,error occurs saying board_pt is undefined. What is the problem? This is the code :

function set_boardPoint( board_pt,turn)
{   
    var no = board_pt.number-1;
    board[no].row = board_pt.row;
    board[no].col = board_pt.col;
    board[no].x = board_pt.x;
    board[no].y = board_pt.y;
    boar开发者_JS百科d[no].value = turn;
    board[no].number = board_pt.number;
}

board is a global array already defined

The problem is that board_pt have only 1 item, and js in these case know board_pt as object:

function set_boardPoint( board_pt,turn)
{   
    var no = board_pt.number-1;
  if( board[no] != undefined ) 
  {
    board[no].row = board_pt.row;
    board[no].col = board_pt.col;
    board[no].x = board_pt.x;
    board[no].y = board_pt.y;
    board[no].value = turn;
    board[no].number = board_pt.number;
}else
{
 board.row = board_pt.row;
    board.col = board_pt.col;
    board.x = board_pt.x;
    board.y = board_pt.y;
    board.value = turn;
    board.number = board_pt.number;
}
}

If board_pt is a real array, then it's unlikely that it has a property named number. Do you mean length?

From your comments, you have to define the previous_boardPoint as an array. To declare a array in javascript, you need to have - var previous_boardPoint = []; in your code. Also have each elements defined (if you have any) like previous_boardPoint[0] = val1; previous_boarPoint[1] = val2; etc.

If these things are not in your code, then in all likely possibilities, you will get board_pt as undefined in your function set_boardPoint.