在JS中拖动多个元素

Question

我是JS的新手，所以我需要帮助来解决我的问题：(。我找到了一个代码笔，它可以帮助我拖动网站的一个元素，但问题是我想分别拖动4个元素。我把同一个类应用于所有这些，但它只适用于第一个。

代码笔的链接：https://codepen.io/Coding-Artist/pen/zYWbYXV

我相信这个解决方案对你来说是显而易见的(我会说var还是for？(但我正在学习，我真的很想进步，所以如果你能解释一下，那就太完美了！非常感谢

JS--

var draggableElem = document.querySelector(".draggable-elem");
let initialX = 0,
initialY = 0;
let moveElement = false;
//events object
let events = {
mouse: {
down: "mousedown",
move: "mousemove",
up: "mouseup"
},
touch: {
down: "touchstart",
move: "touchmove",
up: "touchend"
}
};
let deviceType = "";
//Detect touch device
const isTouchDevice = () => {
try {
//We try to create TouchEvent (it would fail for desktops and throw error)
document.createEvent("TouchEvent");
deviceType = "touch";
return true;
} catch (e) {
deviceType = "mouse";
return false;
}
};
isTouchDevice();
// start(mouse down/touch start)
draggableElem.addEventListener(events[deviceType].down, (e) => {
e.preventDefault();
//initial x and y points
initialX = !isTouchDevice() ? e.clientX : e.touches[0].clientX;
initialY = !isTouchDevice() ? e.clientY : e.touches[0].clientY;
// start movement
moveElement = true;
});
// Move
draggableElem.addEventListener(events[deviceType].move, (e) => {
//if movement==true then set top and left to new X and y while removing any offset
if (moveElement) {
e.preventDefault();
let newX = !isTouchDevice() ? e.clientX : e.touches[0].clientX;
let newY = !isTouchDevice() ? e.clientY : e.touches[0].clientY;
draggableElem.style.top = draggableElem.offsetTop - (initialY - newY) + "px";
draggableElem.style.left =
draggableElem.offsetLeft - (initialX - newX) + "px";
initialX = newX;
initialY = newY;
}
});
//mouse up/touch end
draggableElem.addEventListener(
events[deviceType].up,
(stopMovement = (e) => {
//stop movement
moveElement = false;
})
);
draggableElem.addEventListener("mouseleave", stopMovement);
document.addEventListener(events[deviceType].up, (e) => {
moveElement = false;
});

Answer 1

要使它与多个元素一起工作，您应该为每个元素实例化变量，然后向它们添加事件侦听器。

这可以像我使用document.querySelectorAll和for循环来遍历元素、实例化变量并向每个元素添加事件侦听器一样动态地完成。

我修改过的代码(它并不完美，但它完成了任务(：

let draggableElems = document.querySelectorAll("#draggable-elem");
let initialX = {},
initialY = {};
let moveElement = {};
//events object
let events = {
mouse: {
down: "mousedown",
move: "mousemove",
up: "mouseup"
},
touch: {
down: "touchstart",
move: "touchmove",
up: "touchend"
}
};
let deviceType = "";
//Detect touch device
const isTouchDevice = () => {
try {
//We try to create TouchEvent (it would fail for desktops and throw error)
document.createEvent("TouchEvent");
deviceType = "touch";
return true;
} catch (e) {
deviceType = "mouse";
return false;
}
};
isTouchDevice();
for (let i = 0; i < draggableElems.length; i++) {
var draggableElem = draggableElems[i];
// start(mouse down/touch start)
draggableElem.addEventListener(events[deviceType].down, (e) => {
e.preventDefault();
//initial x and y points
initialX[this] = !isTouchDevice() ? e.clientX : e.touches[0].clientX;
initialY[this] = !isTouchDevice() ? e.clientY : e.touches[0].clientY;
// start movement
moveElement[this] = true;
});
// Move
draggableElem.addEventListener(events[deviceType].move, (e) => {
//if movement==true then set top and left to new X and y while removing any offset
if (moveElement[this]) {
var elem = e.target;
e.preventDefault();
let newX = !isTouchDevice() ? e.clientX : e.touches[0].clientX;
let newY = !isTouchDevice() ? e.clientY : e.touches[0].clientY;
elem.style.top = elem.offsetTop - (initialY[this] - newY) + "px";
elem.style.left = elem.offsetLeft - (initialX[this] - newX) + "px";
initialX[this] = newX;
initialY[this] = newY;
}
});
//mouse up/touch end
draggableElem.addEventListener(
events[deviceType].up,
(stopMovement = (e) => {
//stop movement
moveElement[this] = false;
})
);
draggableElem.addEventListener("mouseleave", stopMovement);
document.addEventListener(events[deviceType].up, (e) => {
moveElement[this] = false;
});
}