话不多说，请看代码：
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>footer定位</title> <style> *{ margin:0; padding: 0; } .box{ width: 100%; height:300px; background: pink; margin-bottom: 30px; } .footer{ background: red; width: 100%; height:30px; } </style> </head> <body> <div> <!--头部开始--> <div> </div> </div> <!--底部--> <div> </div> <script type="text/javascript" src='https://libs.baidu.com/jquery/2.0.0/jquery.js'></script> </body> </html> <script> $(document).ready(function () { var theWindow = $(window); function resized() { var windowSize=window.devicePixelRatio; if(windowSize==1){ var hg2 = $(window).height(); var main = $('.main').outerHeight(); var hg4 = $('.footer').outerHeight(); var hg=hg2-hg4 if( hg > main){ $('.footer').css({"position":'fixed','bottom':0,'left':0,"z-index":999,"width":"100%"}); }else{ $('.footer').css({"position":'static'}); } }else{ $('.footer').css({"position":'static'}); } } theWindow.resize(function () { resized(); }).trigger('resize'); }); </script>