具有奇怪行为的javascript回溯算法

let puzzle = [
    [0, 0, 7, 0, 0, 3, 5, 0, 0],
    [6, 0, 5, 4, 0, 8, 3, 0, 2],
    [0, 0, 4, 5, 2, 0, 9, 0, 6],
    [0, 0, 0, 0, 7, 1, 2, 0, 9],
    [0, 0, 0, 0, 0, 0, 0, 0, 0],
    [8, 0, 9, 2, 3, 0, 0, 0, 0],
    [9, 0, 1, 0, 8, 5, 6, 0, 0],
    [7, 0, 3, 9, 0, 2, 8, 0, 5],
    [0, 0, 8, 7, 0, 0, 1, 0, 0]
];

class Sudoku 
{

    constructor(puzzle) 
    {
        this.sudoku = puzzle;
    }

    isPossible(y, x, n) 
    {
        for (let i = 0; i < 9; i++) 
        {
            if (this.sudoku[y][i] == n)
                return false;
        }

        for (let i = 0; i < 9; i++) 
        {
            if (this.sudoku[i][x] == n)
                return false;
        }

        let y0 = (Math.floor(y / 3) * 3);
        let x0 = (Math.floor(x / 3) * 3);
        
        for (let i = 0; i < 3; i++) 
        {
            for (let j = 0; j < 3; j++) 
            {
                if (this.sudoku[y0 + i][x0 + j] == n)
                    return false;
            }
        }

        return true;
    }

    solve()
    {
        for (let y = 0; y < 9; y++)
        {
            for (let x = 0; x < 9; x++)
            {
                if (this.sudoku[y][x] == 0)
                {
                    for (let n = 1; n <= 9; n++)
                    {
                        if (this.isPossible(y, x, n))
                        {
                            this.sudoku[y][x] = n;
                            this.solve();
                            this.sudoku[y][x] = 0;
                        }
                    }

                    return;
                }
            }
        }

        console.table(this.sudoku);
    }
}

let s = new Sudoku(puzzle);
s.solve();

这本书写得很好.然而，调试表明，在console.table之后，代码继续运行，并将矩阵恢复到其原始状态.但是，再也不会执行console.table行.因此，在solve方法之外，this.sudoku只是原始的puzzle矩阵.