Question

我是JavaScript的新手，并试图构建一个Snake风格的游戏。我在间隔更新函数中有一个条件语句，检查蛇正在移动的方向，它调用Snake对象中的移动方法以保持其运行。最初，我直接在更新功能中使用了这个条件，它按预期工作 - 蛇一直移动直到它撞到墙壁，它会停下来等待不同的方向输入，它会接受并继续向不同的方向前进。

看起来像这样：

//before, with the checks being done in GamePlay.update()
var Snake = (() => {
    let x = 10 * GameBoard.unit;
    let y = 10 * GameBoard.unit;
    let dir = "r";

    let body = [];
    body.unshift({x, y});

    const moveRight = () => {
        x = body[0].x + GameBoard.unit;
        body.unshift({x, y});
        body.pop();
    }

    const moveLeft = () => {
        x = body[0].x - GameBoard.unit;
        body.unshift({x, y});
        body.pop();
    }

    const moveUp = () => {
        y = body[0].y - GameBoard.unit;
        body.unshift({x, y});
        body.pop();
    }

    const moveDown = () => {
        y = body[0].y + GameBoard.unit;
        body.unshift({x, y});
        body.pop();
    }

    return {body, dir, moveLeft, moveRight, moveDown, moveUp};
})();

//inside IIFE called GamePlay
const update = () => {

        if (Snake.dir == "l" && Snake.body[0].x >= GameBoard.LEFT_WALL){
            Snake.moveLeft();
        }
        else if (Snake.dir == "u" && Snake.body[0].y >= GameBoard.TOP_WALL){
            Snake.moveUp();
        }
        else if (Snake.dir == "r" && Snake.body[0].x <= GameBoard.RIGHT_WALL){
            Snake.moveRight();
        }
        else if (Snake.dir == "d" && Snake.body[0].y <= GameBoard.BOTTOM_WALL){
            Snake.moveDown();
        }

    }

为了将代码组织到适当的对象中，我尝试将条件移动移动到Snake对象中，将其放入名为 movement（）的方法中，该方法将从 update（）功能，如下所示：

//after, update conditionals moved from GamePlay.update() to Snake.movement()

var Snake = (() => {
    let x = 10 * GameBoard.unit;
    let y = 10 * GameBoard.unit;
    let dir = "r";

    let body = [];
    body.unshift({x, y});

    const moveRight = () => {
        console.log("in moveRight");
        x = body[0].x + GameBoard.unit;
        body.unshift({x, y});
        body.pop();
    }

    const moveLeft = () => {
        x = body[0].x - GameBoard.unit;
        body.unshift({x, y});
        body.pop();
    }

    const moveUp = () => {
        y = body[0].y - GameBoard.unit;
        body.unshift({x, y});
        body.pop();
    }

    const moveDown = () => {
        y = body[0].y + GameBoard.unit;
        body.unshift({x, y});
        body.pop();
    }

    const movement = () => {
        console.log("called");
        if (dir == "l" && body[0].x >= GameBoard.LEFT_WALL){
            console.log("in l");
            moveLeft();
        }
        else if (dir == "u" && body[0].y >= GameBoard.TOP_WALL){
            console.log("in u");
            moveUp();
        }
        else if (dir == "r" && body[0].x <= GameBoard.RIGHT_WALL){
            console.log("in r");
            moveRight();
        }
        else if (dir == "d" && body[0].y <= GameBoard.BOTTOM_WALL){
            console.log("in d");
            moveDown();
        }
    }

    const alive = () => {
        return true;
    }

    return {body, dir, movement};
})();


// ... in GamePlay
    const update = () => {

        Snake.movement();

    }

然而，这导致在Snake进入右侧墙壁后它的运动停止运转（它在启动时的初始运动是向右的）。在碰到墙之前， console.log（“被叫”）和 console.log（“在r”中）按预期输出，但在击中墙后只有“被叫”日志继续，而“在r中”停止，如果 body [0] .x 大于 GameBoard.RIGHT_WALL ，这将有意义。然后蛇停止接受任何输入，并且不会向上或向下移动，这不应受 body [0] .x 过大的影响。

我的困惑来自这样一个事实，即两种情况下的行为不同，当它是相同的条件代码时，只是重构为一个对象方法，以及为什么当它在外面继续这样做时，它会停止接受方向输入宾语。

javascript - 条件不起作用的函数调用

0 个答案: