javascript - 二维数组赋值中出现意外的 "undefined"元素

Question

下面是我的完整代码。由于某种原因，设置 board[2][0] 时失败，我不明白为什么。我确信这很简单......

function randColor() {
    min = Math.ceil(0);
    max = colors.length;
    return colors[Math.floor(Math.random() * (max - min)) + min]; 
}

const colCount = 10;
const rowCount = 10;

var board = [[],[]];

const colors = ["#f00","#0f0","00f"];

class piece {
    constructor(value, color) {
        this.value = value;
        this.color = color;
    }
}

for (var x = 0; x < colCount; x++) {
    for (var y = 0; y < rowCount; y++) {
        var p = new piece('b',randColor());
        console.log("Setting board[" + x + "][" + y + "]");
        board[x][y] = p;
    }
}

Answer 1

它失败是因为您错误地创建了您的板。它在 2 处失败，因为你有 [[ ],[ ]]。如果你有 [[ ]].. 3 等，它会在 1 处失败。

此外，行是外循环，列是内循环。以下将满足您的需要。

function randColor() {
    min = Math.ceil(0);
    max = colors.length;
    return colors[Math.floor(Math.random() * (max - min)) + min]; 
}

const colCount = 10;
const rowCount = 10;

var board = [];

const colors = ["#f00","#0f0","00f"];

function piece(value, color) {
    this.value = value;
    this.color = color;
}

for (var x = 0; x < rowCount; x++) {
    board[x] = [];
    for (var y = 0; y < colCount; y++) {
        var p = piece('b', randColor());
        console.log("Setting board[" + x + "][" + y + "]");
        board[x][y] = p;
    }
}