JavaScript

//外部スクリプト出力
function getScript(url, targetId){
	var target = document.getElementById(targetId);

	var s = document.createElement("script");
	s.type = "text/javascript";
	s.src = url;
	
	document.body.append(s, target);
}

//Google Adsense用ins出力
function putIns(ins, targetId){
	var target = document.getElementById(targetId);
	
	var new_ele=document.createElement("span");
	var url = '<ins class="adsbygoogle" style="display:inline-block;width:336px;height:280px" data-ad-client="ca-pub-5174440175528623" data-ad-slot="'+ins+'"></ins>';
	new_ele.innerHTML= url;
	
	document.body.append(new_ele, target);
	
	//Google Adsense実行
	(adsbygoogle = window.adsbygoogle || []).push({});
}

HTML

<hr/>
<div id="hoge1">hoge1</div>
<hr/>

<hr/>
<div id="hoge2">hoge2</div>
<hr/>

<script type="text/javascript">
        var ad_ = true;
	if (ad_type == true)
	{
		
		getScript('https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js', "hoge1");
		putIns('Google Adsense広告id', "hoge1");
	}

</script>

<hr/>
<div id="hoge3">hoge3</div>
<hr/>

<hr/>
<div id="hoge4">hoge4</div>
<hr/>

</body>
</html>