如何通过事件侦听器将按键值传递给函数？

Question

我在询问之前已经寻找了现有的答案，但是找不到我想要的东西，或者它已经超出我的头了。

我正在学习JS，想扩展我的课程尚未完全涵盖的内容。基本上，使用vanilla JavaScript，我想将按键与[“ w”，“ a”，“ s”，“ d”]进行比较。

这是我的代码：

function moveCommand(direction) {
    var whatHappens;
    switch (direction) {
        case direction === event.key["w"]:
            var outcome = battle(1) ? "run your sword through it! Gain 25 exp!" : "take serious damage. Gain 5exp. Lose 20hp.";
            whatHappens = "You encounter a monster and " + outcome;
            break;
        case direction === event.key["a"]:
            whatHappens = "You arrived home";
            break;
        case direction === event.key["s"]:
            // player.gold += 15;
            whatHappens = "You found 15 gold!";
            break;
        case direction === event.key["d"]:
            var outcome = battle(2) ? "send it packing! Gain 10exp!" : "get pelted with stones. Gain 2exp. Lose 10hp.";
            whatHappens = "You run into a troll and " + outcome;
            break;
        default:
            whatHappens = "Please enter a valid direction";
    }
    return whatHappens;
}

document.addEventListener('keypress', moveCommand);

我理解为什么这不起作用（按键可能没有传递给'direction'，并且我检查event.key的语法可能不正确），但是我找不到如何使它起作用。如果没有jQuery或其他扩展名，它甚至可能吗？

Answer 1

switch语句以及如何处理事件存在问题，请通读文档以了解如何使用switch statements，请注意，对于按下事件，switch语句在case内不需要条件， event.key已经返回了按键的字母，这是我制作的一个片段，以展示如何使其工作，由于您不包括它，因此我删除了battle()，这是一个有效的片段：

function moveCommand(event) {
    var whatHappens;
    switch (event.key) {
        case 'w':
            var outcome = 1 ? "run your sword through it! Gain 25 exp!" : "take serious damage. Gain 5exp. Lose 20hp.";
            whatHappens = "You encounter a monster and " + outcome;
            break;
        case 'a':
            whatHappens = "You arrived home";
            break;
        case 's':
            // player.gold += 15;
            whatHappens = "You found 15 gold!";
            break;
        case 'd':
            var outcome = 1 ? "send it packing! Gain 10exp!" : "get pelted with stones. Gain 2exp. Lose 10hp.";
            whatHappens = "You run into a troll and " + outcome;
            break;
        default:
            whatHappens = "Please enter a valid direction";
    }
    console.log(whatHappens)
}

document.addEventListener('keypress', moveCommand);