Why doesn't Safari decodeURIcomponent() a URI-encoded piece of JSON automatically, like Firefox?

I'm passing a URI-encoded JSON string from secure iFrame to a non-secure grandparent iFrame. When it reaches the parent, I parse it using YUI's

 YAHOO.lang.JSON.parse()

In Firefox, this works perfectly, and my string looks like

     "{\"CntctNm\":\"Mike\",

In Safari, it looks like

    "{%22CntctNm%22:%22Mike%22,

and

YAHOO.lang.JSON.parse() chokes.

So, how viable is my hackaroun开发者_如何学Cd of looking for URI encoding, and decoding the string if I find it?

if(JSONstr){
  secrJsonResp.indexOf("22:%22")>-1;
  var updtJsonObj = Cmn.ParseJSON(decodeURIComponent(JSONstr));
}else{
  var updtJsonObj = Cmn.ParseJSON(JSONstr);
};