@H_301_0@本文实例讲述了javascript实现拖动元素交换位置的代码。分享给大家供大家参考。具体如下：
@H_3010@
实现目标：
可拖动元素拖动到另外一个元素位置的时候，互相交换位置。@H301_0@
启发来源：
最初形式是网上看到的一个拼图小游戏。 @H_301_0@运行效果截图如下：
var oBox = document.getElementById("Box");
var aLi = oBox.getElementsByTagName("li");
var aPos = [];
var aData = [];
for (i = 0; i < 15; i++)aData.push(i+1);
//插入结构
var oFragment = document.createDocumentFragment();
for (i = 0; i < aData.length; i++) {
var oLi = document.createElement("li");
oFragment.appendChild(oLi)
}
oBox.appendChild(oFragment);
//布局转换
for (i = 0; i < aLi.length; i++) {
aLi[i].index = i;
aLi[i].style.top = aLi[i].offsetTop + "px";
aLi[i].style.left = aLi[i].offsetLeft + "px";
aLi[i].style.margin = "0 5px 5px 0";
aPos.push({
"left": aLi[i].offsetLeft,"top": aLi[i].offsetTop
})
}
for (i = 0; i < aLi.length; i++) {
aLi[i].style.position = "absolute";
drag(aLi[i])
}
//拖拽函数
function drag(obj,handle) {
var handle = handle || obj;
handle.style.cursor = "move";
handle.onmousedown = function(event) {
var event = event || window.event;
var disX = event.clientX - this.offsetLeft;
var disY = event.clientY - this.offsetTop;
var oNear = null;
obj.style.zIndex = zIndex++;
document.onmousemove = function(event) {
var event = event || window.event;
var iL = event.clientX - disX;
var iT = event.clientY - disY;
var maxL = obj.parentNode.clientWidth - obj.offsetWidth;
var maxT = obj.parentNode.clientHeight - obj.offsetHeight;
iL < 0 && (iL = 0);
iT < 0 && (iT = 0);
iL > maxL && (iL = maxL);
iT > maxT && (iT = maxT);
obj.style.left = iL + "px";
obj.style.top = iT + "px";
for (i = 0; i < aLi.length; i++) aLi[i].className = "";
oNear = findNearest(obj);
oNear && (oNear.className = "hig");
return false
};
document.onmouseup = function() {
document.onmousemove = null;
document.onmouseup = null;
if (oNear) {
var tIndex = obj.index;
obj.index = oNear.index;
oNear.index = tIndex;
startMove(obj,aPos[obj.index]);
startMove(oNear,aPos[oNear.index],function() {
});
oNear.className = "";
} else {
startMove(obj,aPos[obj.index])
}
handle.releaseCapture && handle.releaseCapture()
};
this.setCapture && this.setCapture();
return false
}}
//找出相遇点中最近的元素
function findNearest(obj) {
var filterLi = [];
var aDistance = [];
for (i = 0; i < aLi.length; i++) aLi[i] != obj && (isButt(obj,aLi[i]) && (aDistance.push(getDistance(obj,aLi[i])),filterLi.push(aLi[i])));
var minNum = Number.MAX_VALUE;
var minLi = null;
for (i = 0; i < aDistance.length; i++) aDistance[i] < minNum && (minNum = aDistance[i],minLi = filterLi[i]);
return minLi}
};
//求两点之间的距离
function getDistance(obj1,obj2) {
var a = (obj1.offsetLeft + obj1.offsetWidth / 2) - (obj2.offsetLeft + obj2.offsetWidth / 2);
var b = (obj1.offsetTop + obj1.offsetHeight / 2) - (obj2.offsetTop + obj2.offsetHeight / 2);
return Math.sqrt(a a + b b)
}
//碰撞检测
function isButt(obj1,obj2) {
var l1 = obj1.offsetLeft;
var t1 = obj1.offsetTop;
var r1 = obj1.offsetLeft + obj1.offsetWidth;
var b1 = obj1.offsetTop + obj1.offsetHeight;
var l2 = obj2.offsetLeft;
var t2 = obj2.offsetTop;
var r2 = obj2.offsetLeft + obj2.offsetWidth;
var b2 = obj2.offsetTop + obj2.offsetHeight;
return !(r1 < l2 || b1 < t2 || r2 < l1 || b2 < t1)
}
//获取最终样式
function getStyle(obj,attr) {
return parseFloat(obj.currentStyle ? obj.currentStyle[attr] : getComputedStyle(obj,null)[attr])
}
//运动框架
function startMove(obj,pos,onEnd) {
clearInterval(obj.timer);
obj.timer = setInterval(function() {
doMove(obj,onEnd)
},30)
}
function doMove(obj,onEnd) {
var iCurL = getStyle(obj,"left");
var iCurT = getStyle(obj,"top");
var iSpeedL = (pos.left - iCurL) / 5;
var iSpeedT = (pos.top - iCurT) / 5;
iSpeedL = iSpeedL > 0 ? Math.ceil(iSpeedL) : Math.floor(iSpeedL);
iSpeedT = iSpeedT > 0 ? Math.ceil(iSpeedT) : Math.floor(iSpeedT);
if (pos.left == iCurL && pos.top == iCurT) {
clearInterval(obj.timer);
onEnd && onEnd()
} else {
obj.style.left = iCurL + iSpeedL + "px";
obj.style.top = iCurT + iSpeedT + "px";
}
}
