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问题:
This is my updated and modified script, it works completely, except I would like to universalize it... observe the **** how can I make it so that I don't have to do function(e){BOX.Draggable.elemen = e.target || e.srcElement; elementDraggable(e); everytime I need to use the dragable function for a different element?
window.onload = addListeners;
var BOX = function(){
return{
Draggable: function(){}
};
}();
function addListeners(){
document.getElementById('div').addEventListener('contextmenu', menumove, false);
**document.getElementById('div').addEventListener('mousedown', function(e){BOX.Draggable.elemen = e.target || e.srcElement; elementDraggable(e);}, false);**
}
function elementDraggable(e){
var e = e || window.event;
var div = BOX.Draggable.elemen;
BOX.Draggable.innerX = e.clientX + window.pageXOffset - div.offsetLeft;
BOX.Draggable.innerY = e.clientY + window.pageYOffset - div.offsetTop;
window.addEventListener('mousemove', elementMove, false);
window.addEventListener('mouseup', function(){
window.removeEventListener('mousemove', elementMove, false);
}, true);
function elementMove(e){
div.style.position = 'absolute';
div.style.left = e.clientX + window.pageXOffset - BOX.Draggable.innerX + 'px';
div.style.top = e.clientY + window.pageYOffset - BOX.Draggable.innerY + 'px';
}
}
回答1:
Is jQuery an option for you? It makes what you are doing really simple since the code already exists.
http://jqueryui.com/demos/draggable/
Demo
JavaScript Code
window.onload = addListeners;
function addListeners(){
document.getElementById('dxy').addEventListener('mousedown', mouseDown, false);
window.addEventListener('mouseup', mouseUp, false);
}
function mouseUp()
{
window.removeEventListener('mousemove', divMove, true);
}
function mouseDown(e){
window.addEventListener('mousemove', divMove, true);
}
function divMove(e){
var div = document.getElementById('dxy');
div.style.position = 'absolute';
div.style.top = e.clientY + 'px';
div.style.left = e.clientX + 'px';
}
回答2:
This is a nice no-jQuery script to drag a div: http://jsfiddle.net/g6m5t8co/1/
<!doctype html>
<html>
<head>
<style>
#container {
position:absolute;
background-color: blue;
}
#elem{
position: absolute;
background-color: green;
-webkit-user-select: none;
-moz-user-select: none;
-o-user-select: none;
-ms-user-select: none;
-khtml-user-select: none;
user-select: none;
}
</style>
<script>
var mydragg = function(){
return {
move : function(divid,xpos,ypos){
divid.style.left = xpos + 'px';
divid.style.top = ypos + 'px';
},
startMoving : function(divid,container,evt){
evt = evt || window.event;
var posX = evt.clientX,
posY = evt.clientY,
divTop = divid.style.top,
divLeft = divid.style.left,
eWi = parseInt(divid.style.width),
eHe = parseInt(divid.style.height),
cWi = parseInt(document.getElementById(container).style.width),
cHe = parseInt(document.getElementById(container).style.height);
document.getElementById(container).style.cursor='move';
divTop = divTop.replace('px','');
divLeft = divLeft.replace('px','');
var diffX = posX - divLeft,
diffY = posY - divTop;
document.onmousemove = function(evt){
evt = evt || window.event;
var posX = evt.clientX,
posY = evt.clientY,
aX = posX - diffX,
aY = posY - diffY;
if (aX < 0) aX = 0;
if (aY < 0) aY = 0;
if (aX + eWi > cWi) aX = cWi - eWi;
if (aY + eHe > cHe) aY = cHe -eHe;
mydragg.move(divid,aX,aY);
}
},
stopMoving : function(container){
var a = document.createElement('script');
document.getElementById(container).style.cursor='default';
document.onmousemove = function(){}
},
}
}();
</script>
</head>
<body>
<div id='container' style="width: 600px;height: 400px;top:50px;left:50px;">
<div id="elem" onmousedown='mydragg.startMoving(this,"container",event);' onmouseup='mydragg.stopMoving("container");' style="width: 200px;height: 100px;">
<div style='width:100%;height:100%;padding:10px'>
<select id=test>
<option value=1>first
<option value=2>second
</select>
<INPUT TYPE=text value="123">
</div>
</div>
</div>
</body>
</html>
回答3:
Well, your movement code simplifies to:
div.style.position = "absolute";
div.style.top = e.clientY - (e.clientY - div.offsetTop) + "px";
div.style.left = e.clientX - (e.clientX - div.offsetLeft) + "px";
Basic math here - the e.clientX and e.clientY have absolutely no effect on the position here, so you're just taking the offsetLeft and reassigning it to the style.left, and the same for the top. Thus no movement whatsoever.
What you need to do is save the clientX and clientY when the mousedown happens, and do the subtraction based on that.
Oh and you're also setting the event listener wrong. The way it is now, you have it run divMove once and the return value (undefined here) is the function attached as the listener. Instead, use function(e) {divMove(dxy,e || window.event);}.
回答4:
I modified Shaedo's code a little bit, wraps it in a function and add a feature that you can drag an element by only parts of it or its children, say the title bar of a div. Note in this demo, you can only drag the red area to move the blue area.
function makeDragable(dragHandle, dragTarget) {
let dragObj = null; //object to be moved
let xOffset = 0; //used to prevent dragged object jumping to mouse location
let yOffset = 0;
document.querySelector(dragHandle).addEventListener("mousedown", startDrag, true);
document.querySelector(dragHandle).addEventListener("touchstart", startDrag, true);
/*sets offset parameters and starts listening for mouse-move*/
function startDrag(e) {
e.preventDefault();
e.stopPropagation();
dragObj = document.querySelector(dragTarget);
dragObj.style.position = "absolute";
let rect = dragObj.getBoundingClientRect();
if (e.type=="mousedown") {
xOffset = e.clientX - rect.left; //clientX and getBoundingClientRect() both use viewable area adjusted when scrolling aka 'viewport'
yOffset = e.clientY - rect.top;
window.addEventListener('mousemove', dragObject, true);
} else if(e.type=="touchstart") {
xOffset = e.targetTouches[0].clientX - rect.left;
yOffset = e.targetTouches[0].clientY - rect.top;
window.addEventListener('touchmove', dragObject, true);
}
}
/*Drag object*/
function dragObject(e) {
e.preventDefault();
e.stopPropagation();
if(dragObj == null) {
return; // if there is no object being dragged then do nothing
} else if(e.type=="mousemove") {
dragObj.style.left = e.clientX-xOffset +"px"; // adjust location of dragged object so doesn't jump to mouse position
dragObj.style.top = e.clientY-yOffset +"px";
} else if(e.type=="touchmove") {
dragObj.style.left = e.targetTouches[0].clientX-xOffset +"px"; // adjust location of dragged object so doesn't jump to mouse position
dragObj.style.top = e.targetTouches[0].clientY-yOffset +"px";
}
}
/*End dragging*/
document.onmouseup = function(e) {
if (dragObj) {
dragObj = null;
window.removeEventListener('mousemove', dragObject, true);
window.removeEventListener('touchmove', dragObject, true);
}
}
}
makeDragable('#handle', '#moveable')
#moveable {
width: 100px;
height: 100px;
background: blue;
}
#handle {
width: 50px;
height: 50px;
cursor: move;
background: red;
}
<div id="moveable">
<div id="handle">
</div>
</div>
回答5:
After trying jnoreiga's accepted answer, I found it very annoying that the dragged element abruptly snapped to the top left corner, rather than maintaining the same relative position.
This snippet prevents the awkward aforementioned behavior via an offset, and provides a simple interface to create draggable elements one at a time or en masse via a forEach call or similar.
window.onload = function() {
draggable(document.getElementById('foo'));
}
function draggable(el) {
el.addEventListener('mousedown', function(e) {
var offsetX = e.clientX - parseInt(window.getComputedStyle(this).left);
var offsetY = e.clientY - parseInt(window.getComputedStyle(this).top);
function mouseMoveHandler(e) {
el.style.top = (e.clientY - offsetY) + 'px';
el.style.left = (e.clientX - offsetX) + 'px';
}
function reset() {
window.removeEventListener('mousemove', mouseMoveHandler);
window.removeEventListener('mouseup', reset);
}
window.addEventListener('mousemove', mouseMoveHandler);
window.addEventListener('mouseup', reset);
});
}
/* The only required styling is position: absolute */
#foo {
position: absolute;
border: 1px solid black;
overflow: hidden;
}
/* Prevents inconsistent highlighting of element while being dragged
Copied from https://stackoverflow.com/questions/826782 */
.noselect {
-webkit-touch-callout: none; /* iOS Safari */
-webkit-user-select: none; /* Safari */
-khtml-user-select: none; /* Konqueror HTML */
-moz-user-select: none; /* Firefox */
-ms-user-select: none; /* Internet Explorer/Edge */
user-select: none; /* Non-prefixed version, currently
supported by Chrome and Opera */
}
<div id="foo" class="noselect">This is a draggable div!</div>
回答6:
An additional method to "niente00" code.
init : function(className){
var elements = document.getElementsByClassName(className);
for (var i = 0; i < elements.length; i++){
elements[i].onmousedown = function(){mydragg.startMoving(this,'container',event);};
elements[i].onmouseup = function(){mydragg.stopMoving('container');};
}
}
