通过我的代码当我需要在canvas上下棋(描点)时,显示(里面的4只是我点击的点对应的property)
Uncaught TypeError: Cannot set property '4' of undefined
at Gobang._next
at HTMLCanvasElement.<anonymous>
我的部分代码如下:
html部分:
<div id="chessboard_container" class="chessboard-container hidden"></div>
<div id="chessboard_canvas_container" class="chessboard-canvas-container ">
<canvas id="chessboard_bg_canvas" width="458" height="458"></canvas>
<canvas id="chessboard_shadow_canvas" width="458" height="458"></canvas>
<canvas id="chessboard_canvas" width="458" height="458"></canvas>
</div>
js部分:
function Gobang() {
this._status = 0; // 棋局状态,0表示对战中,1表示对战结束
this._role = 0; // 棋子颜色,0表示黑棋,1表示白棋
this._chessDatas = []; // 存放下棋数据
this._chessboardDatas = [];//存放棋盘数据
this._chessCanvas = document.getElementById('chessboard_canvas');
this._chessContext = this._chessCanvas.getContext('2d');
};
/**
* 在canvas落子
*/
Gobang.prototype._drawChessInCanvas = function(position,role) {
var vm = this;
if(position == undefined || position == null) return;
var x = 4 + ((position % 15) + 0.5) * 30;
var y = 4 + (parseInt((position / 15), 10) + 0.5) * 30;
vm._chessContext.beginPath();
vm._chessContext.arc(x, y, 13, 0, 2 * Math.PI);// 画圆
//定义棋子颜色
if(role){
vm._chessContext.fillStyle = "#FFF";
}else{
vm._chessContext.fillStyle = "#000";
}
vm._chessContext.fill();
vm._chessContext.closePath();
};
/**
* 落子
*/
Gobang.prototype._drawChess = function(position) {
var vm = this;
if (position === undefined || position === null) return;
vm._drawChessInCanvas(position, vm._role);
};
/**
* 下一步棋
*/
Gobang.prototype._next = function(position) {
var vm = this;
if(vm._hasChess(position)) return;
vm._chessboardDatas[(position % 15)][parseInt((position / 15), 10)] = vm._role;
vm._chessDatas.push(position);
// 绘制棋子
vm._drawChess(position,vm._role);
};
vm._chessCanvas.addEventListener('click', function(e) {
var x = e.offsetX;
var y = e.offsetY;
var i = Math.floor((x - 4) / 30);
var j = Math.floor((y - 4) / 30);
var position = i + j * 15;
if(vm._status == 0) {
vm._next(position);
vm._role = 1 - vm._role;
}
}, false);
请问我的代码如何改,才能正常实现下棋的效果。