JS动态修改CSS浏览器兼容问题

最近搞的一个JS动态改变CSS内容,和大家分享。

<script type="text/javascript">
  function GetCurrentStyle (obj, prop,num) {
     if (obj.currentStyle) {
     if (num==0) {
     document.styleSheets[0].cssText=document.styleSheets[0].cssText.replace(/19em/g,"1em");
     }
     else {
     document.styleSheets[0].cssText=document.styleSheets[0].cssText.replace(/1em/g,"19em");
     }
   }
     else if (window.getComputedStyle) {
     if (num==0) {
     document.styleSheets[0].cssRules[0].style.cssText=document.styleSheets[0].cssRules[0].style.cssText.replace(/19em/g,"0em");
     }
     else {
    document.styleSheets[0].cssRules[0].style.cssText=document.styleSheets[0].cssRules[0].style.cssText.replace(/0em/g,"19em");
     }
     }
     return null;
}    
function showSiterbar(){

    var b=document.getElementById('leftColumn')
    var c=document.getElementById('content')
if(b.style.display=="block"){
     GetCurrentStyle(c,"margin-left",0);    
     b.style.display="none";
}else{
   GetCurrentStyle(c,"margin-left",1);
   b.style.display="block";
}
}
</script>