html 标签的src属性 含有变量

1
<script type="text/javascript" >
var   path   =   "";
<script type="text/javascript" >
document.write( " <img src="+path+"/images/gdj_img/top.gif>");
</script>

2
<img id=imgid src="+path+"/images/gdj_img/top.gif>


<script type="text/javascript" src="url.js" id="myscript"></script>

<script type="text/javascript">
        var mys = document.getElementById("imgid");
        mys.src = path;
</script>