原生JavaScript实现拖拽功能

实现

 (function(window, document){
    var x=0,y=0,element;
    window.startDarg = function(targeId){
        element= document.getElementById(targeId).bind(document);
        element.attachEvent("onmousedown", mousedownFun)
    }
    function mousedownFun(e){
        e=e||window.event;
        x=e.clientX - this.offsetLeft;
        y=e.clientY - this.offsetTop;
        document.addEventListener("onmousemove", mousemoveFun);
        document.addEventListener("onmouseup", mouseupFun);
    }
    function mousemoveFun(e){
        e=e||window.event;
        setStyle(element, {left: e.clientX - x + "px", top: e.clientY -y + "px"});
    }
    function mouseupFun(){
        document.removeEventListener('onmousemove', mousemoveFun);
        document.removeEventListener('onmouseup', mouseupFun);
    }
    function setStyle(element, css) {
        for (var k in css) {
            if (css.hasOwnProperty(k)) {
                element.style[k] = css[k]
            }
        }
     }
})(window, document)

讲解

1. 关注三个事件：mousedown，mousemove，mouseup。当目标元素触发鼠标按下时，启动拖拽方法。因为鼠标存在过快的情况，所以鼠标移动和鼠标释放时作用在document上的。
2. 当鼠标移动时，重新更新目标元素的top和left。
3. 当鼠标释放时，取消鼠标移动事件的处理方法。

本文地址：https://blog.csdn.net/baidu_38798835/article/details/107525676