<input name="a"><button onclick="javascript:var tmp = showModalDialog('aa.html');document.all.a.value = tmp;">
</button>
aa.html
<input type="text" name="bb">
<button onclick="window.returnValue=document.all.bb.value;window.close()">
</button>
aa.html
<input type="text" name="bb">
<button onclick="window.returnValue=document.all.bb.value;window.close()">
window.onload=function(){
opener.document.all.obj.value=返回的值
}
</script>