获取元素高度并比较大小
window.onload = function(){
var smain= document.getElementById("sideBarMain");
var addd= document.getElementById("sidebar_ad");
var mainaa= document.getElementById("main");
var style3= window.getComputedStyle(document.getElementById("mainContent"), null);
var style5= window.getComputedStyle(document.getElementById("sideBar"), null);
if(style3.height > 945+'px' ||style3.height.length > 5){
addd.style.height = style3.height ;
smain.style.height = style3.height ;
mainaa.style.height = style3.height ;
}else{
addd.style.height = style5.height ;
smain.style.height = style5.height ;
mainaa.style.height = style5.height ;
}
}
</script>