简单拖拽代码
简单拖拽代码
提问于 2013-08-25 02:27:12
我挣扎于一个看似简单的javascript练习，写一个香草的拖放。我想我对我的“addeventlisteners”犯了一个错误，下面是代码：
var ele = document.getElementsByClassName ("target")[0];
var stateMouseDown = false;
//ele.onmousedown = eleMouseDown;
ele.addEventListener ("onmousedown" , eleMouseDown , false);
function eleMouseDown () {
stateMouseDown = true;
document.addEventListener ("onmousemove" , eleMouseMove , false);
}
function eleMouseMove (ev) {
do {
var pX = ev.pageX;
var pY = ev.pageY;
ele.style.left = pX + "px";
ele.style.top = pY + "px";
document.addEventListener ("onmouseup" , eleMouseUp , false);
} while (stateMouseDown === true);
}
function eleMouseUp () {
stateMouseDown = false;
document.removeEventListener ("onmousemove" , eleMouseMove , false);
document.removeEventListener ("onmouseup" , eleMouseUp , false);
}回答 4
Stack Overflow用户
回答已采纳
发布于 2013-08-25 02:58:13
下面是对它起作用的一个小动作：http://jsfiddle.net/fpb7j/1/
有两个主要问题，首先是onmousedown、onmousemove和onmouseup的使用。我相信这些只适用于附带的事件：
document.body.attachEvent('onmousemove',drag);mousedown、mousemove和mouseup用于事件侦听器：
document.body.addEventListener('mousemove',drag);第二个问题是move事件函数中的do-while循环。每次鼠标移动像素时都会调用该函数，因此不需要循环：
var ele = document.getElementsByClassName ("target")[0];
ele.addEventListener ("mousedown" , eleMouseDown , false);
function eleMouseDown () {
stateMouseDown = true;
document.addEventListener ("mousemove" , eleMouseMove , false);
}
function eleMouseMove (ev) {
var pX = ev.pageX;
var pY = ev.pageY;
ele.style.left = pX + "px";
ele.style.top = pY + "px";
document.addEventListener ("mouseup" , eleMouseUp , false);
}
function eleMouseUp () {
document.removeEventListener ("mousemove" , eleMouseMove , false);
document.removeEventListener ("mouseup" , eleMouseUp , false);
}顺便说一句，我必须使目标的位置绝对有效。
Stack Overflow用户
发布于 2014-02-11 06:30:29
你也可以试试这把小提琴，http://jsfiddle.net/dennisbot/4AH5Z/
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>titulo de mi pagina</title>
<style>
#target {
width: 100px;
height: 100px;
background-color: #ffc;
border: 2px solid blue;
position: absolute;
}
</style>
<script>
window.onload = function() {
var el = document.getElementById('target');
var mover = false, x, y, posx, posy, first = true;
el.onmousedown = function() {
mover = true;
};
el.onmouseup = function() {
mover = false;
first = true;
};
el.onmousemove = function(e) {
if (mover) {
if (first) {
x = e.offsetX;
y = e.offsetY;
first = false;
}
posx = e.pageX - x;
posy = e.pageY - y;
this.style.left = posx + 'px';
this.style.top = posy + 'px';
}
};
}
</script>
</head>
<body>
<div id="target" style="left: 10px; top:20px"></div>
</body>
</html>Stack Overflow用户
发布于 2016-09-02 19:12:34
我刚做了个简单的累赘。
这是一种一行用法，它处理诸如鼠标偏移到元素左上角、onDrag/onStop回调和SVG元素拖放之类的操作。
这是密码。
// simple drag
function sdrag(onDrag, onStop) {
var startX = 0;
var startY = 0;
var el = this;
var dragging = false;
function move(e) {
el.style.left = (e.pageX - startX ) + 'px';
el.style.top = (e.pageY - startY ) + 'px';
onDrag && onDrag(el, e.pageX, startX, e.pageY, startY);
}
function startDragging(e) {
if (e.currentTarget instanceof HTMLElement || e.currentTarget instanceof SVGElement) {
dragging = true;
var left = el.style.left ? parseInt(el.style.left) : 0;
var top = el.style.top ? parseInt(el.style.top) : 0;
startX = e.pageX - left;
startY = e.pageY - top;
window.addEventListener('mousemove', move);
}
else {
throw new Error("Your target must be an html element");
}
}
this.addEventListener('mousedown', startDragging);
window.addEventListener('mouseup', function (e) {
if (true === dragging) {
dragging = false;
window.removeEventListener('mousemove', move);
onStop && onStop(el, e.pageX, startX, e.pageY, startY);
}
});
}
Element.prototype.sdrag = sdrag;并利用它：
document.getElementById('my_target').sdrag();还可以使用onDrag和onStop回调：
document.getElementById('my_target').sdrag(onDrag, onStop);在这里查看我的回购以获得更多细节：https://github.com/lingtalfi/simpledrag
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/18425089
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