無法讀取未定義的屬性'xPos'（JavaScript）

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我正在嘗試使用JavaScript和[p5] [1]製作迷宮生成器。每次我運行的代碼，雖然它說：無法讀取未定義的屬性'xPos'（JavaScript）

遺漏的類型錯誤：在抽獎（sketch.js：24）無法讀取的不確定財產「XPOS」 ......

並且還，那隻能說明我的無聊電網。我一直試圖解決這個問題，我找不到解決方案。這裏是我的代碼：

Sketch.js：

var cellSize = 32; 
 
var cols = 20; 
 
var rows = 20; 
 
var grid = create2DArray(cols, rows); 
 

 
var stack = []; 
 
var currentCell = grid[0][0]; 
 

 
function setup() { 
 
    createCanvas(cols * cellSize, rows * cellSize); 
 

 
    generateCells(); 
 
} 
 

 
function draw() { 
 
    background(230); 
 

 
    for (var x = 0; x < cols; x++) { 
 
    for (var y = 0; y < rows; y++) { 
 
     grid[x][y].draw(); 
 
    } 
 
    } 
 

 
    randomNeighbor(currentCell.xPos/cellSize, currentCell.y/cellSize); 
 
} 
 

 
function create2DArray(c, r) { 
 
    var arr = new Array(c); 
 

 
    for (var i = 0; i < c; i++) { 
 
    arr[i] = new Array(r); 
 
    } 
 

 
    return arr; 
 
} 
 
function generateCells() { 
 
    for (var x = 0; x < cols; x++) { 
 
    for (var y = 0; y < rows; y++) { 
 
     var cell = new Cell(x * cellSize, y * cellSize); 
 
     grid[x][y] = cell; 
 
    } 
 
    } 
 

 
} 
 
function randomCell() { 
 
    var randomX = floor(random(0, cols)); 
 
    var randomY = floor(random(0, rows)); 
 
    var cell = grid[randomX][randomY]; 
 
    grid[randomX][randomY].visited = true; 
 

 
    return cell; 
 
} 
 
function randomNeighbor(x, y) { 
 
    if (getMoveable(x, y)) { 
 
    append(stack, currentCell); 
 

 
    var neighbors = []; 
 
    if (x - 1 >= 0) append(neighbors, grid[x-1][y]); 
 
    if (x + 1 <= cols) append(neighbors, grid[x+1][y]); 
 
    if (y - 1 >= 0) append(neighbors, grid[x][y - 1]); 
 
    if (y + 1 <= rows) append(neighbors, grid[x][y+1]); 
 
    var rand = floor(random(0, neighbors.length)); 
 

 
    currentCell = neighbors[rand]; 
 

 
    removeWall(currentCell, stack[stack.length]); 
 
    } 
 
    else { 
 
    currentCell = stack.pop(); 
 
    } 
 
} 
 
function getMoveable(x, y) { 
 
    var moveable = false; 
 

 
    var neighbors = []; 
 
    if (x - 1 >= 0) append(neighbors, grid[x-1][y]); 
 
    if (x + 1 <= cols) append(neighbors, grid[x+1][y]); 
 
    if (y - 1 >= 0) append(neighbors, grid[x][y - 1]); 
 
    if (y + 1 <= rows) append(neighbors, grid[x][y+1]); 
 
    for (var i = 0; i < neighbors.length; i++) { 
 
    if (neighbors[i].visited == true) { 
 
     moveable = true; 
 
     break; 
 
    } 
 
    } 
 

 
    return moveable; 
 
} 
 
function removeWall(a, b) { 
 
    if (a.xPos - b.xPos == -cellSize) { 
 
    grid[a.xPos/cellSize][a.yPos/cellSize].right = false; 
 
    } 
 
    else if (a.xPos - b.xPos == cellSize) { 
 
    grid[b.xPos/cellSize][b.yPos/cellSize].right = false; 
 
    } 
 
    else if (a.yPos - b.yPos == -cellSize) { 
 
    grid[a.xPos/cellSize][a.yPos/cellSize].bottom = false; 
 
    } 
 
    else if (a.yPos - b.yPos == cellSize) { 
 
    grid[b.xPos/cellSize][b.yPos/cellSize].bottom = false; 
 
    } 
 
}

Cell.js：

function Cell(xx, yy) { 
 
    this.xPos = xx; 
 
    this.yPos = yy; 
 
    this.visited = false; 
 

 
    this.right = true; 
 
    this.bottom = true; 
 

 
    this.draw = function() { 
 
    stroke(0); 
 
    strokeWeight(1); 
 

 
    if (this.right) { 
 
     line(this.xPos + cellSize, this.yPos, this.xPos + cellSize, this.yPos + cellSize); 
 
    } 
 
    if (this.bottom) { 
 
     line(this.xPos, this.yPos + cellSize, this.xPos + cellSize, this.yPos + cellSize); 
 
    } 
 
    } 
 
}

index.html的（事情我在我的瀏覽器中打開）：

<!DOCTYPE html> 
 
<html> 
 
    <head> 
 
    <script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.5.11/p5.min.js"></script> 
 
    <script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.5.11/addons/p5.dom.min.js"></script> 
 
    <script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.5.11/addons/p5.sound.min.js"></script> 
 
    <script src="cell.js"></script> 
 
    <script src="sketch.js"></script> 
 
    <style> body {padding: 0; margin: 0;} </style> 
 
    </head> 
 
    <body> 
 
    </body> 
 
</html>

來源

2017-06-12 Xephyr

當你做var currentCell = grid[0][0];，該grid數組是空的，所以currentCell變得undefined。

function generateCells() { 
    for (var x = 0; x < cols; x++) { 
    for (var y = 0; y < rows; y++) { 
     var cell = new Cell(x * cellSize, y * cellSize); 
     grid[x][y] = cell; 
    } 
    } 
    currentCell = grid[0][0]; 
}

來源

2017-06-12 18:43:47

，修復了錯誤，但現在有一個新的：遺漏的類型錯誤：無法讀取性能在getMoveable（草圖的不確定「參觀」您填寫的grid與細胞您應該儘快更新currentCell。 js：81） – Xephyr

我會盡力解決這個問題... – Xephyr

@NumNumDude在將一個元素附加到'neighbors'數組之前，你必須檢查它是否存在。 –

無法讀取未定義的屬性'xPos'（JavaScript）

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