Javascript递归意外中断-警告长代码

我对以下代码有问题。在NewMaze中的maze函数的递归过程中，它似乎正在中断。我通过firebug运行了它，得到以下错误：

parent is undefined: line 97 newmaze_generator.js
    [Break On This Error] self.visited = function() {return parent.visited();}; 

我不知道为什么它会是未定义的，如果这是真正的问题的话

我知道这要求很多，所以请不要浪费你的时间，除非你真的想帮助一个新手javascript程序员。为了让事情变得更简单，我在我的网站上有完整的代码，这样你就可以实际运行这个程序，而这个程序目前什么也做不了

另一方面，这只是我第二次涉足javascript编程，所以我很容易犯下愚蠢的错误

我的MazeGenerator

function NewMaze(_grid) {
    var self = this;
    var stack = new Array();
    var grid = _grid;

    /**
     * A recursive depth-first-search style maze generator
     */
    self.maze = function() {
        var randx = Math.floor(Math.random()*(grid.getWidth()));
        var randy = Math.floor(Math.random()*(grid.getHeight()));
        var startOfMaze = new MyCell(grid.getCell(randx, randy));
        stack.push(startOfMaze);
        mazeHelper(startOfMaze);
    };

    /**
     * Internal recursive method used by maze.
     * A depth-first-search style algorithm.
     * @param mycell current cell
     * @returns {Boolean} true once finished
     */
    function mazeHelper(myCell) {
        var neighbors = myCell.getOpenNeighbors();
        myCell.markVisited();
        if (neighbors.length > 0) {
            var next = Math.floor(Math.random()*(neighbors.length));
            var nextCell = neighbors[next];
            stack.push(nextCell);
            removeWall(myCell, nextCell);
//          alert(myCell.getParent().getArrayLocation().getX()+" , "+myCell.getParent().getArrayLocation().getY());
            mazeHelper(nextCell);
        } else {
            alert("else");
            if (stack.length == 0) return true;
            else mazeHelper(stack.pop());
        };
    };

    /**
     * Removes the wall between the given cells
     * @param fromCell
     * @param toCell
     */
    function removeWall(fromCell, toCell) {
        var xDif = toCell.getParent().getArrayLocation().getX() - fromCell.getParent().getArrayLocation().getX();
        var yDif = toCell.getParent().getArrayLocation().getY() - fromCell.getParent().getArrayLocation().getY();

        if (xDif == -1) toCell.seWall = false;  // if moving up x axis
        if (xDif == 1) fromCell.seWall = false; // if moving down x axis
        if (yDif == -1) toCell.swWall = false;  // if moving up y axis
        if (yDif == 1) fromCell.swWall = false; // if moving down y axis

    };

    /**
     * @returns an instance of 'this' named self.
     */
    self.getSelf = function() {return self;};

    /**
     * Inner class that is an extension of Cell class
     * @param cell the parent cell
     * @returns {MyCell} instance of 'this' child
     */
    function MyCell(cell) {
        var self = this;
        var parent = cell;

        /**
         * Marks the referenced cell as visited using the super class's visited method.
         */
        self.markVisited = function() {parent.markVisited();};

        self.visited = function() {return parent.visited();};

        /**
         * Creates and returns an array of neighbors that have not been visited.
         * @returns {<MyCell>Array} an array of adjacent cells that have not been visited. 
         */
        self.getOpenNeighbors = function() {
            var neighbors = new Array();

            var tc0, tc1, tc3, tc4;
            var parentX = parent.getArrayLocation().getX();
            var parentY = parent.getArrayLocation().getY();

            tc0 = new MyCell(grid.getCell(parentX-1, parentY));
            tc1 = new MyCell(grid.getCell(parentX+1, parentY));
            tc2 = new MyCell(grid.getCell(parentX, parentY-1));
            tc3 = new MyCell(grid.getCell(parentX, parentY+1));

            if (tc0 != undefined && !tc0.visited()) neighbors.push(tc0);
            if (tc1 != undefined && !tc1.visited()) neighbors.push(tc1);
            if (tc2 != undefined && !tc2.visited()) neighbors.push(tc2);
            if (tc3 != undefined && !tc3.visited()) neighbors.push(tc3);

            return neighbors;
        };

        /**
         * @returns an instance of 'this' named self.
         */
        self.getSelf = function() {return self;};

        /**
         * @returns an instance of the 'super' class named parent.
         */
        self.getParent = function() {return parent;};
    };
};

---

好吧，我知道了！我犯了一个愚蠢的错误，我不确定这是否是件好事

问题是：

在getOpenNeights函数中，我正在检查单元格是否未定义，如果未定义，请不要将其添加到可能要移动到的邻居数组中。嗯，未定义的支票写得不正确。我将这些单元格定义为：

tc0 = new MyCell(grid.getCell(parentX-1, parentY));

如果给定位置不存在单元格，则grid.getCell（x，y）方法将返回undefined，这正是我希望它执行的操作

但是，在检查中，我确保没有将其添加到我编写的数组中：

if (tc0 != undefined && !tc0.visited()) neighbors.push(tc0);

很明显，我以这种方式创建的tc0或任何tc0-x对象都不会是未定义的。我需要做的是检查作为参数传递的对象是否未定义。我将这个对象视为父类或超类，所以我所要做的就是使用我的方法getParent（），一切都会很顺利

if (tc0.getParent() != undefined && !tc0.visited()) neighbors.push(tc0);

---

现在一切都好了！不幸的是，迷宫看起来不像它应该的样子，所以我要在那里解决一些问题，但至少我现在可以前进了

据我所知，您的“单元格”没有与之关联的已访问方法。由于它们是myCell对象的父对象，因此未定义parent.visited（）。cell类具有以下方法：self.visited=function（）{return visited；}；此后，我在迷宫生成器的内部类MyCell的已访问函数中添加了一个try-catch，我正在捕获没有父对象的对象，我只是不明白为什么会发生这种情况。

if (tc0 != undefined && !tc0.visited()) neighbors.push(tc0);

if (tc0.getParent() != undefined && !tc0.visited()) neighbors.push(tc0);