1.如何禁用页面元素拖出去
οndragstart="return false;" //禁止鼠标拖动，如拖动图片、连接等
例如：
<body οndragstart="return false;" οncοntextmenu="return false;">
2.如何禁用拖元素进入页面
<script>
document.ondrop = function(event) {
return false;
};
document.ondragenter = function(event) {
return false;
};
document.ondragover = function(event) {
return false;
};
</script>
参考资料：
https://blog.csdn.net/OrangeJuiceMe/article/details/64125068
https://cloud.tencent.com/developer/article/1476542