Javascript 阻止页面选中效果

  // 阻止页面选中效果
  document.onmousedown=function () {
    document.onmousemove=function () {
      window.getSelection ? window.getSelection().removeAllRanges() : document.selection.empty();
    }
  }
  document.onmouseup=function () {
    document.onmousemove = null;
  }