function seed() {
    return Array.prototype.slice.call(arguments);
}

function same([x, y], [j, k]) {
    return x === j && y === k;
}

// The game state to search for `cell` is passed as the `this` value of the function. 
function contains(cell) {
    return this.some(c => same(c, cell));
}

const sum = ([x, y], [j, k]) => [x + j, y + k];

const getNeighborsOf = ([x, y]) => {
    const neighborDeltas = [
        [-1, 1],
        [0, 1],
        [1, 1],
        [-1, 0], /* */ , [1, 0],
        [-1, -1],
        [0, -1],
        [1, -1]
    ];
    return neighborDeltas.map((d) => sum(d, [x, y]));
}

const livingNeighbors = getLivingNeighbors(cell, state);

return (
    livingNeighbors.length === 3 ||
    contains.call(state, cell) && livingNeighbors.length === 2);
}

const corners = (state = []) => {
    const xs = state.map(([x, _]) => x);
    const ys = state.map(([_, y]) => y);
    return {
        topRight: [Math.max(...xs), Math.max(...ys)],
        bottomLeft: [Math.min(...xs), Math.min(...ys)]
    };
};


const calculateNext = (state) => {
    const { bottomLeft, topRight } = corners(state);
    let result = [];
    for (let y = topRight[1] + 1; y >= bottomLeft[1] - 1; y--) {
        for (let x = bottomLeft[0] - 1; x <= topRight[0] + 1; x++) {
            result = result.concat(isAlive([x, y], state) ? [
                [x, y]
            ] : []);
        }
    }
    return result;
};

const printCell = (cell, state) => {
    return contains.call(state, cell) ? 'x' : '_';
};

const printCells = (state) => {
    const { bottomLeft, topRight } = corners(state);
    for (let y = topRight[1]; y >= bottomLeft[1]; y--) {
        let row = [];
        for (let x = bottomLeft[0]; x <= topRight[0]; x++) {
            row.push(printCell([x, y], state));
        }
        console.log(row.join(''));
    }
};

exports.seed = seed;
exports.same = same;
exports.contains = contains;
exports.sum = sum;
exports.getNeighborsOf = getNeighborsOf;
exports.getLivingNeighbors = getLivingNeighbors;
exports.isAlive = isAlive;
exports.corners = corners;
exports.calculateNext = calculateNext;
exports.printCell = printCell;
exports.printCells = printCells;

I am getting an error.

In this project you will build a simple two dimensional simulation of living cells, known as Conway’s Game of Life. In the process you will learn all about JavaScript functions, including what you can do with them and their many features.