如何跟踪按下按钮的时间?JavaScript

Question

我需要你的帮助。在以下代码的帮助下，我试图检测按下Delete键的时间。我的代码没有给我任何错误，但它不能很好地工作。例如，如果我按下按键3秒，它显示的时间就会完全不同。告诉我我做错了什么，我的错在哪里?非常感谢。

var startTime;
document.body.onkeydown = function() {
const key = event.key;
if (key === 'Delete') {
console.log('key down');
startTime = +new Date();
}
}
document.body.onkeyup = function() {
const key = event.key;
if (key === 'Delete') {
console.log('key up')
var endTime = +new Date();
var time = (endTime - startTime) / 1000;
if (time > 3) {
console.log('cool')
}
console.log(time + ' sec');
}
}

Answer 1

您可以使用您设置的小标记忽略多次重复。

var startTime;
var delete_down = false;
document.body.onkeydown = function(ev) {
const key = event.key;
if (key === 'Delete') {
ev.preventDefault();
if (delete_down) {
return
}
delete_down = true;
console.log('key down');
startTime = +new Date();
}
}
document.body.onkeyup = function() {
const key = event.key;
if (key === 'Delete') {
console.log('key up')
delete_down = false;
var endTime = +new Date();
var time = (endTime - startTime) / 1000;
if (time > 3) {
console.log('cool')
}
console.log(time + ' sec');
}
}

click me then hit [Del]