拖动效果实现

1.利用js实现

//获取当前鼠标在页面上的坐标
function getPointerPositionInDocument(eventObject) {
    var x = eventObject.pageX;
    var y = eventObject.pageY;
    return {
        'x': x,
        'y': y
    };
}
//获取元素在页面上的位置
function getDimensions(element){
    return {
        'left':element.offsetLeft,
        'top':element.offsetTop,
        'width':element.offsetWidth,
        'height':element.offsetHeight
    };
}

2.利用HTML5+JS

新增属性:draggable

新增事件:ondragstart(拖动开始) ondrag(拖动中) ondragend(拖动结束)

ondragenter(进入投放去区) ondragover(投放去移动) ondragleave(离开投放区) ondrop(投放区投放)

HTML部分：

<div id="dropBlock"></div>
<div id="moveBlock" draggable="true"></div>

JS部分：

(function(){
        var dropBlock = document.getElementById("dropBlock");
        var moveBlock = document.getElementById("moveBlock");
        var moveBlockInitPos = getDimensions(moveBlock);
        var startPoint;
        var moveBlockPos;
        moveBlock.ondragstart = function(){
            var e = getEventObject(e);
            //获取鼠标点击时的坐标
            startPoint = getPointerPositionInDocument(e)
            //获取移动块的位置
            moveBlockPos = getDimensions(moveBlock);
        }
//        moveBlock.ondrag = function(){
//            console.log("拖拽中");
//        }
//        moveBlock.ondragend = function(){
//            console.log("拖拽结束");
//        }
//        dropBlock.ondragenter = function(){
//            console.log("进入投放区");
//        }
        dropBlock.ondragover = function(e){
            console.log("投放区移动");
            //阻止默认事件发生
            e.preventDefault();
        }
//        dropBlock.ondragleave = function(){
//            console.log("离开投放区");
//        }
        dropBlock.ondrop = function(e){
            var e = getEventObject(e);
            var newPoint = getPointerPositionInDocument(e);
            var distance = getPointerDistance(startPoint,newPoint);
            moveBlock.style.left = (moveBlockPos.left + distance.x)+"px";
            moveBlock.style.top = (moveBlockPos.top + distance.y)+"px";
            //阻止事件冒泡
            e.stopPropagation();
        }
        document.ondragover = function(e){
            var e = getEventObject(e);
            //阻止默认事件发生
            e.preventDefault();
        }
        document.ondrop = function(e){
            var e = getEventObject(e);
            console.log("进入文档投放区");

            moveBlock.style.left = moveBlockInitPos.left+"px";
            moveBlock.style.top = moveBlockInitPos.top +"px";
        }
    }())