实现拖拽一个元素
拖拽的流程：
当鼠标在被拖拽元素上按下时，开始拖拽 onmousedown
当鼠标移动时被拖拽元素跟随鼠标移动 onmousemove
当鼠标松开时，被拖拽元素固定在当前位置 onmouseup
<style> #box1{ width: 100px; height: 100px; background-color: red; position: absolute; } </style> <body> <div id="box1"></div> </body> </html> <script type="text/javascript"> window.onload = function(){ var box1 = document.getElementById("box1"); //为box1绑定一个鼠标按下事件,当鼠标在被拖拽元素上按下时，开始拖拽 onmousedown box1.onmousedown = function(event){ event = event || window.event; //div的偏移量 鼠标.clentX - 元素.offsetLeft //div的偏移量 鼠标.clentY - 元素.offsetTop var ol = event.clientX - box1.offsetLeft; var ot = event.clientY - box1.offsetTop; //为document绑定一个onmousemove事件 document.onmousemove = function(event){ event = event || window.event; //当鼠标移动时被拖拽元素跟随鼠标移动 onmousemove //获取鼠标的坐标 var left = event.clientX - ol; var top = event.clientY - ot; //修改box1的位置 box1.style.left = left+"px"; box1.style.top = top+"px"; }; //为document绑定一个鼠标松开事件 document.onmouseup = function(){ //当鼠标松开时，被拖拽元素固定在当前位置 onmouseup //取消document的onmousemove事件 document.onmousemove = null; //取消document的onmouseup事件 document.onmouseup = null; }; }; }; </script>