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66 DOCTYPE html html head Meta charset title无标题文档title style bodymargin padding #to_topwidth30px height40px padding20px font14px20px arial textaligncenter background#06c positionabsolute cursorpointer color#fff style script 页面加载后触发 window. btn document. timer isTop 获取页面可视区高度 clientHeight document.. window. 显示回到顶部按钮 osTop document.. document.. osTop = clientHeight btn.. btn.. 用户滚动滚动条，停止定时器 isTop clearIntervaltimer isTop btn. timer setInterval 获取滚动条距离顶部高度 osTop document.. document.. ispeed .osTop document.. document.. osTopispeed osTop clearIntervaltimer isTop script head body style h1返回顶部的按钮在下面h1 div stylediv div id返回顶部div body html
