让iframe自适应高度

 <iframe id="mainiframe" width="100%" height="600" src="/dsdd/confirm/"  frameborder="0" scrolling="auto"></iframe>

function changeFrameHeight(){
        var ifm= document.getElementById("mainiframe");
        ifm.height=document.documentElement.clientHeight-56;   //56是头顶的高度，

} window.onresize=function(){ changeFrameHeight();} $(function(){changeFrameHeight();});