如何不用jQuery库执行iframe src修改代码

<script>
    window.onload = function() {
        let iframeObj = document.querySelector('#WANG iframe');

        if (iframeObj) {
            var src = iframeObj.src;

            var newParams = "&id=" + "{$obj.vod_id}" + "&name=" + {$obj.vod_name}-{$obj['vod_play_list'][$param['sid']]['urls'][$param['nid']]['name']} + "&group=" + "{$GLOBALS['_COOKIE']['group_name']}" + "&next=" + "{$obj.player_info.url_next}" + "&sid=" + "{$param.sid}" + "&nid=" + "{$param.nid}" + "&api=" + "https://www.suying.lol/index.php" + "&dmId=" + "{$obj.player_info.url}";

            var newSrc = src.replace("&if=1", "&if=1" + newParams);

            iframeObj.setAttribute('src', newSrc);
        } else {
            console.error("Cannot find iframe with id 'WANG'");
        }
    };
</script>
<p>这样就可以在页面加载完成后执行代码，修改相应的iframe的src属性值。</p>