[]如何动态在index.html加入script

请问要在index.html中加入如下的程式码该怎么做呢？

<!--启动类添加到这里-->

	<script type="text/javascript" src="main.min.js"></script>

	<script type="text/javascript" src="main.js"></script>

	<script>

    var gameCanvas = document.getElementById("layaCanvas");

    if ((sys.platform !== sys.DESKTOP_BROWSER)) {

        gameCanvas.style.position = "fixed";

    } else {

        gameCanvas.style.position = "static";

    }

    html5Full.toLandscape();

</script>

这边，我知道创建script标签的方法

var body = laya.utils.Browser.window.document.getElementsByTagName("body")[0];



let script = laya.utils.Browser.window.document.createElement('script');

body.appendChild(script);

但是我不知如何在script中加入如下程式码

<script>

    var gameCanvas = document.getElementById("layaCanvas");

    if ((sys.platform !== sys.DESKTOP_BROWSER)) {

        gameCanvas.style.position = "fixed";

    } else {

        gameCanvas.style.position = "static";

    }

    html5Full.toLandscape();

</script>