I have developed a unique drag and drop application that features both a left and right panel. The issue I am facing is that when I drag the ball from the left panel to the right panel, it does get dragged successfully. However, the problem arises when the ball gets removed from the left panel while being dragged. What I want is for the ball to only be draggable/movable to the right panel, without the possibility of going back to the left panel. Below is the code snippet:
let currentDroppable = null;
ball.onmousedown = function(event) {
let shiftX = event.clientX - ball.getBoundingClientRect().left;
let shiftY = event.clientY - ball.getBoundingClientRect().top;
ball.style.position = 'absolute';
ball.style.zIndex = 1000;
document.body.append(ball);
moveAt(event.pageX, event.pageY);
function moveAt(pageX, pageY) {
ball.style.left = pageX - shiftX + 'px';
ball.style.top = pageY - shiftY + 'px';
}
function onMouseMove(event) {
moveAt(event.pageX, event.pageY);
ball.hidden = true;
let elemBelow = document.elementFromPoint(event.clientX, event.clientY);
ball.hidden = false;
if (!elemBelow) return;
let droppableBelow = elemBelow.closest('.droppable');
if (currentDroppable != droppableBelow) {
if (currentDroppable) { // null when we were not over a droppable before this event
leaveDroppable(currentDroppable);
}
currentDroppable = droppableBelow;
if (currentDroppable) { // null if we're not coming over a droppable now
// (maybe just left the droppable)
enterDroppable(currentDroppable);
}
}
}
document.addEventListener('mousemove', onMouseMove);
ball.onmouseup = function() {
document.removeEventListener('mousemove', onMouseMove);
ball.onmouseup = null;
};
};
function enterDroppable(elem) {
elem.style.background = 'pink';
}
function leaveDroppable(elem) {
elem.style.background = '';
}
ball.ondragstart = function() {
return false;
};#gate {
cursor: pointer;
margin-bottom: 100px;
width: 83px;
height: 46px;
border: 1px solid;
}
#ball {
cursor: pointer;
width: 40px;
height: 40px;
}<div style="float:left;border: 1px solid;width: 15%;">Left Pannel<img src="https://en.js.cx/clipart/ball.svg" id="ball"></div>
<div style="float: left;border: 1px solid;width: 80%;height: 1000px;">Right Panel</div>