var solveSudoku = function (board) {
 // let rows = new Array(9).fill(new Array(10).fill(0)),
 let rows = new Array(9);
 for (let i = 0; i < 9; i++) {
 rows[i] = new Array(10).fill(0);
 }
 let cols = new Array(9);
 for (let i = 0; i < 9; i++) {
 cols[i] = new Array(10).fill(0);
 }
 let boxes = new Array(9);
 for (let i = 0; i < 9; i++) {
 boxes[i] = new Array(10).fill(0);
 }
 // let cols = new Array(9).fill(new Array(10).fill(0)),
 // boxes = new Array(9).fill(new Array(10).fill(0));
 for (let i = 0; i < 9; i++) {
 for (let j = 0; j < 9; j++) {
 let c = board[i][j];
 if (c !== '.') {
 let n = parseInt(c),
 bx = Math.floor(j / 3),
 by = Math.floor(i / 3);
 // 0代表为使用,1为使用过
 rows[i][n] = 1;
 console.log(i, n)
 cols[j][n] = 1;
 // box索引
 boxes[by * 3 + bx][n] = 1;
 }
 }
 }
 
 fill(board, 0, 0)
 
 function fill(board, x, y) {
 // 完成填充条件
 if (y === 9) return true; 
 // 下一个点的坐标
 let nx = (x + 1) % 9,
 // 判断进入是否下一行
 ny = (nx === 0) ? y + 1 : y;
 // 如果已经填充,则进入下一个点
 if (board[y][x] !== '.') return fill(board, nx, ny);
 // 没有被填充过
 for (let i = 1; i <= 9; i++) {
 let bx = Math.floor(x / 3),
 by = Math.floor(y / 3),
 box_key = by * 3 + bx;
 if (!rows[y][i] && !cols[x][i] && !boxes[box_key][i]) {
 rows[y][i] = 1;
 cols[x][i] = 1;
 boxes[box_key][i] = 1;
 board[y][x] = i.toString();
 console.log(board[y][x])
 // 递归向下一个点求解
 if (fill(board, nx, ny)) return true;
 // 恢复初始状态
 board[y][x] = '.';
 boxes[box_key][i] = 0;
 rows[y][i] = 0;
 cols[x][i] = 0;
 }
 }
 return false;
 }
 console.log(board);
};

guys! I'm new to JavaScript, I'm trying to solve leetcode question 37. I need to a create a blank two dimensional array, I initially used the method in the comments; however, it doesn't work correctly, it will change all the value. Then, I used the for loop method to create array and currently it worked correctly. But I still cannot figured out why this will happen, could anyone explain the reason why this will happen, is this because of shallow copy?

var solveSudoku = function (board) {
 // let rows = new Array(9).fill(new Array(10).fill(0)),
 let rows = new Array(9);
 for (let i = 0; i < 9; i++) {
 rows[i] = new Array(10).fill(0);
 }
 let cols = new Array(9);
 for (let i = 0; i < 9; i++) {
 cols[i] = new Array(10).fill(0);
 }
 let boxes = new Array(9);
 for (let i = 0; i < 9; i++) {
 boxes[i] = new Array(10).fill(0);
 }
 // let cols = new Array(9).fill(new Array(10).fill(0)),
 // boxes = new Array(9).fill(new Array(10).fill(0));
 for (let i = 0; i < 9; i++) {
 for (let j = 0; j < 9; j++) {
 let c = board[i][j];
 if (c !== '.') {
 let n = parseInt(c),
 bx = Math.floor(j / 3),
 by = Math.floor(i / 3);
 // 0代表为使用,1为使用过
 rows[i][n] = 1;
 console.log(i, n)
 cols[j][n] = 1;
 // box索引
 boxes[by * 3 + bx][n] = 1;
 }
 }
 }
 fill(board, 0, 0)
 function fill(board, x, y) {
 // 完成填充条件
 if (y === 9) return true; 
 // 下一个点的坐标
 let nx = (x + 1) % 9,
 // 判断进入是否下一行
 ny = (nx === 0) ? y + 1 : y;
 // 如果已经填充,则进入下一个点
 if (board[y][x] !== '.') return fill(board, nx, ny);
 // 没有被填充过
 for (let i = 1; i <= 9; i++) {
 let bx = Math.floor(x / 3),
 by = Math.floor(y / 3),
 box_key = by * 3 + bx;
 if (!rows[y][i] && !cols[x][i] && !boxes[box_key][i]) {
 rows[y][i] = 1;
 cols[x][i] = 1;
 boxes[box_key][i] = 1;
 board[y][x] = i.toString();
 console.log(board[y][x])
 // 递归向下一个点求解
 if (fill(board, nx, ny)) return true;
 // 恢复初始状态
 board[y][x] = '.';
 boxes[box_key][i] = 0;
 rows[y][i] = 0;
 cols[x][i] = 0;
 }
 }
 return false;
 }
 console.log(board);
};

I'm new to JavaScript, I'm trying to solve leetcode question 37. I need to a create a blank two dimensional array, I initially used the method in the comments; however, it doesn't work correctly, it will change all the value. Then, I used the for loop method to create array and currently it worked correctly. But I still cannot figured out why this will happen, could anyone explain the reason why this will happen, is this because of shallow copy?

var solveSudoku = function (board) {
 // let rows = new Array(9).fill(new Array(10).fill(0)),
 let rows = new Array(9);
 for (let i = 0; i < 9; i++) {
 rows[i] = new Array(10).fill(0);
 }
 let cols = new Array(9);
 for (let i = 0; i < 9; i++) {
 cols[i] = new Array(10).fill(0);
 }
 let boxes = new Array(9);
 for (let i = 0; i < 9; i++) {
 boxes[i] = new Array(10).fill(0);
 }
 // let cols = new Array(9).fill(new Array(10).fill(0)),
 // boxes = new Array(9).fill(new Array(10).fill(0));
 for (let i = 0; i < 9; i++) {
 for (let j = 0; j < 9; j++) {
 let c = board[i][j];
 if (c !== '.') {
 let n = parseInt(c),
 bx = Math.floor(j / 3),
 by = Math.floor(i / 3);
 // 0代表为使用,1为使用过
 rows[i][n] = 1;
 console.log(i, n)
 cols[j][n] = 1;
 // box索引
 boxes[by * 3 + bx][n] = 1;
 }
 }
 }
 
 fill(board, 0, 0)
 
 function fill(board, x, y) {
 // 完成填充条件
 if (y === 9) return true; 
 // 下一个点的坐标
 let nx = (x + 1) % 9,
 // 判断进入是否下一行
 ny = (nx === 0) ? y + 1 : y;
 // 如果已经填充,则进入下一个点
 if (board[y][x] !== '.') return fill(board, nx, ny);
 // 没有被填充过
 for (let i = 1; i <= 9; i++) {
 let bx = Math.floor(x / 3),
 by = Math.floor(y / 3),
 box_key = by * 3 + bx;
 if (!rows[y][i] && !cols[x][i] && !boxes[box_key][i]) {
 rows[y][i] = 1;
 cols[x][i] = 1;
 boxes[box_key][i] = 1;
 board[y][x] = i.toString();
 console.log(board[y][x])
 // 递归向下一个点求解
 if (fill(board, nx, ny)) return true;
 // 恢复初始状态
 board[y][x] = '.';
 boxes[box_key][i] = 0;
 rows[y][i] = 0;
 cols[x][i] = 0;
 }
 }
 return false;
 }
 console.log(board);
};