JavaScript多重按键 [英] JavaScript multiple keydown

问题描述

首先，我要感谢大家的帮助和答复.

First, I would like to thank all for your help and replies.

我正在开发一个项目，要求用户按下一个键并按住它，它将触发一个动作.

I'm working on a project that required users to press a key and hold it, it will trigger an action.

当用户按下另一个键(仍然按住第一个键)时，它将触发另一个动作.

When the user presses another key ( still holing the first key), it will trigger another action.

但是，我一直无法让JavaScript识别同时按下的两个键.

However, I'm stuck getting JavaScript to recognize two keys being pressed at the same time.

var down = false;
var keys;

document.addEventListener("keydown", function (e) {
    if (down) {return;}
    down = true;
    keys = (keys || []);
    keys[e.keyCode]=true;
    if (keys[87]){
        console.log("1");

    }
    else if (keys[83]){
        console.log("2");
    }
    else if (keys[83] && keys[87]){
        console.log("sucessfull");
    }
} , false);

document.addEventListener("keyup", function (e) {
    down = false;
    keys[e.keyCode]=false;
    stop();
}, false);

<button id="up" onmousedown="Drive(1)" onmouseup="Drive(2)">UP </button>

推荐答案

1. 删除了向下"变量检查
2. 删除了鼠标按钮元素-似乎与您的问题无关?
3. 删除了多余的HTML正文

4. 摆脱了其他分支，因为在到达&&&之前，它会被满足(87或83).条件

1. Removed the 'down' variable checks
2. Removed the mouse button element thing - didn't seem relevant to your problem?
3. Removed the extra HTML body

4. Got rid of the else branching as it would be satisfied (by 87 or 83) before ever getting to the && condition

    var keys;

    document.addEventListener("keydown", function (e) {
        keys = (keys || []);
        keys[e.keyCode]=true;
        if (keys[87]){
            console.log("1");

        }

        if (keys[83]){
            console.log("2");
        }

        if (keys[83] && keys[87]){
            console.log("sucessfull");
        }
    } , false);

    document.addEventListener("keyup", function (e) {
        keys[e.keyCode]=false;
        stop();
    }, false);

这篇关于JavaScript多重按键的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！