ConnectFour_GameChecking Method Signatures

connectFour.js

function chkLine(a,b,c,d) {
    // Check first cell non-zero and all cells match
    return ((a != 0) && (a ==b) && (a == c) && (a == d));
}

function chkWinner(bd) {
    // Check down
    for (r = 0; r < 3; r++)
        for (c = 0; c < 7; c++)
            if (chkLine(bd[r][c], bd[r+1][c], bd[r+2][c], bd[r+3][c]))
                return bd[r][c];

    // Check right
    for (r = 0; r < 6; r++)
        for (c = 0; c < 4; c++)
            if (chkLine(bd[r][c], bd[r][c+1], bd[r][c+2], bd[r][c+3]))
                return bd[r][c];

    // Check down-right
    for (r = 0; r < 3; r++)
        for (c = 0; c < 4; c++)
            if (chkLine(bd[r][c], bd[r+1][c+1], bd[r+2][c+2], bd[r+3][c+3]))
                return bd[r][c];

    // Check down-left
    for (r = 3; r < 6; r++)
        for (c = 0; c < 4; c++)
            if (chkLine(bd[r][c], bd[r-1][c+1], bd[r-2][c+2], bd[r-3][c+3]))
                return bd[r][c];

    return 0;
}

// TEST CALL:

x =[ [0, 0, 0, 0, 0, 0, 0],
     [0, 0, 0, 0, 0, 0, 0],
     [0, 0, 0, 1, 1, 0, 0],
     [0, 0, 0, 1, 1, 0, 0],
     [0, 0, 1, 2, 2, 2, 0],
     [0, 1, 2, 2, 1, 2, 0] ];
alert(chkWinner(x));