SOURCE

var me = true;
var over = false;
var chessBox = [];
var wins = [];  //定义三维数组
//赢法统计数组
var myWin = [];
var computerWin = [];
for(i=0;i<15;i++){
 chessBox[i]=[];
 for(j=0;j<15;j++){
 chessBox[i][j]=0;
 } 
}
for(var i=0;i<15;i++){
 wins[i]=[];
 for(var j=0;j<15;j++){
 wins[i][j]=[];
 }
}
var count =0;
//所有横线
for(var i=0;i<15;i++){
 for(var j=0;j<11;j++){
 //执行1次
 // wins[0][0][0]=true;
 // wins[0][1][0]=true;
 // wins[0][2][0]=true;
 // wins[0][3][0]=true;
 // wins[0][4][0]=true;
 //执行2次
 // wins[0][1][1]=true;
 // wins[0][2][1]=true;
 // wins[0][3][1]=true;
 // wins[0][4][1]=true;
 // wins[0][5][1]=true;
 for(var k=0; k<5;k++){
 wins[i][j+k][count] = true;
 }
 count++;
 }
}
console.log(1111,wins[0])
//所有竖线
for(var i=0;i<15;i++){
 for(var j=0;j<11;j++){
 for(var k=0; k<5;k++){
 wins[j+k][i][count] = true;
 }
 count++;
 }
}
//所有斜线
for(var i=0;i<11;i++){
 for(var j=0;j<11;j++){
 for(var k=0; k<5;k++){
 wins[i+k][j+k][count] = true;
 }
 count++;
 }
}
//所有反斜线
for(var i=0;i<11;i++){
 for(var j=14;j>3;j--){
 for(var k=0; k<5;k++){
 wins[i+k][j-k][count] = true;
 }
 count++;
 }
}
  console.log(1111,wins[0][0],wins[0][0].length)
console.log(count);
for (var i=0;i<count;i++) {
 myWin[i] = 0;
 computerWin[i] = 0;
}
  
var chess = document.getElementById('chess');
var context = chess.getContext('2d');
context.strokeStyle = "#BFBFBF";
var logo= new Image();
// logo.src = "https://img.jbzj.com/file_images/article/202005/2020528104036640.jpg";
logo.src = "https://img0.baidu.com/it/u=391913564,1144083768&fm=253&fmt=auto&app=138&f=JPEG?w=800&h=500";

logo.onload = function(){
 context.drawImage(logo,0,0,450,450);
 drawChessBoard();
// oneStep(0,0,true);
// oneStep(1,1,false);
}
function drawChessBoard(){
 for(var i=0;i<15;i++){
 context.moveTo(15+i*30,15);
 context.lineTo(15+i*30,435);
 context.moveTo(15,15+i*30);
 context.lineTo(435,15+i*30);
 context.stroke();
 }
  
}
var oneStep = function(i,j,me){
 context.beginPath();
 context.arc(15+i*30,15+j*30,13,0,2*Math.PI);
 context.closePath();
 var gradient = context.createRadialGradient(15+i*30,15+j*30,30,15+i*30,15+j*30,0);
 if(me){
 gradient.addColorStop(0,"#0A0A0A");
 gradient.addColorStop(1,"#636766");
 }else{
 gradient.addColorStop(0,"#D1D1D1");
 gradient.addColorStop(1,"#F9F9F9");
 }
  
 context.fillStyle = gradient;
 context.fill();
}
  
chess.onclick = function(e){
    if(over){
    return;
    }
    if(!me){
    return;
    }
    var x = e.offsetX;
    var y = e.offsetY;
    console.log(1111,x,y)
    var i = Math.floor(x/30); //i,j为索引序列号
    var j = Math.floor(y/30);
    console.log(1111,i,j)
    if(chessBox[i][j]==0){
        oneStep(i,j,me);
        chessBox[i][j]=1;
        for(var k=0;k < count; k++){
            if(wins[i][j][k]) {
                myWin[k]++;
                computerWin[k] = 6; //设置异常值
                if(myWin[k] == 5) {
                    window.alert("你赢了");
                    over = true;
                }
            }
        }
        if(!over){
            me=!me;
            computerAI();
        }
    } 
  
}
var computerAI = function(){
 var myScore = [];
 var computerScore = [];
 var max = 0; //保存最高分数；
 var u = 0, v =0; //保存坐标
 for(var i=0;i<15;i++){
 myScore[i] = [];
 computerScore [i] = [];
 for(var j=0;j<15;j++){
 myScore[i][j] = 0;
 computerScore[i][j] = 0;
 }
 }
 for (var i=0; i<15;i++) {
 for (var j=0;j<15;j++) {
 if(chessBox[i][j] == 0){
 for(var k =0 ;k<count;k++){
 if(wins[i][j][k]){
 if(myWin[k]==1){
 myScore[i][j]+= 200;
 }else if(myWin[k]==2){
 myScore[i][j]+= 400;
 }else if(myWin[k]==3){
 myScore[i][j]+= 2000;
 }else if(myWin[k]==4){
 myScore[i][j]+= 10000;
 }
 if(computerWin[k]==1){
 computerScore[i][j]+= 220;
 }else if(computerWin[k]==2){
 computerScore[i][j]+= 420;
 }else if(computerWin[k]==3){
 computerScore[i][j]+= 2020;
 }else if(computerWin[k]==4){
 computerScore[i][j]+= 10020;
 }
 }
 }
 if(myScore[i][j]>max){
 max = myScore[i][j];
 u = i;
 v = j;
 }else if(myScore[i][j] == max){
 if(computerScore[i][j] > computerScore[u][v]){
 u = i;
 v = j;
 }
 }
 if(computerScore[i][j]>max){
 max = computerScore[i][j];
 u = i;
 v = j;
 }else if(computerScore[i][j] == max){
 if(myScore[i][j] > myScore[u][v]){
 u = i;
 v = j;
 }
 }
 }
 }
 }
 oneStep(u,v,false);
 chessBox[u][v] = 2;
 for(var k=0;k < count; k++){
 if(wins[u][v][k]) {
 computerWin[k]++;
 myWin[k] = 6; //设置异常值
 if(computerWin[k] == 5) {
 window.alert("计算机赢了");
 over = true;
 }
 }
 }
 if(!over){
 me=!me; 
 }
}

<html>
 <head>
 <meta charset="utf-8" />
 <title>五子棋</title>

 </head>
 <body>
 <canvas id="chess" width="450px" height="450px"></canvas>
 </body>
</html>

canvas{
 display: block;
 margin: 50px auto;
 box-shadow: -2px -2px 2px #EFEFEF,5px 5px 5px #B9B9B9;
}