如何在将数据发送到Facebook之前替换发送网址？

Question

如何在将数据发送到Facebook之前替换发送网址？

单击facebook btn时我需要替换url。怎么做？

<fb:like href="%my_url" layout="standard" action="like" show_faces="true" share="true"></fb:like>
<fb:share-button href="%my_url" type="button_count"></fb:share-button>

<script type="text/javascript">
    /* ------- 
        when click facebook button , before send data to facebook,
        i need to replace the "%my_url" string to my pointed url , then send to facebook
        any facebook function to do this job?
     ------- */
    FB.???(
        this.url = replace('%my_url','http://www.google.com');
    )

</script>