function FacebookUtil(iframe){
    this.iframe = $(iframe);
    this.init();
    window.onresize = function(){
        facebookUtil.init();
    };
}

FacebookUtil.prototype.init = function(){
    var width  = this.iframe.parentNode.getWidth();
    width -= parseInt(this.iframe.parentNode.getStyle("padding-left"), 10);
    width -= parseInt(this.iframe.parentNode.getStyle("padding-right"), 10);
    this.setFacebookUrlParam('width', width);
    this.iframe.width = width; //({width: width});
}

FacebookUtil.prototype.setFacebookUrlParam = function(param, value){
    var src = this.iframe.src.unescapeHTML();
    this.iframe.src = src.replace(new RegExp("("+param+"=)[^&]*", "gi"), "$1"+value);
}