Supposing that:
1. You have a _Layout.cshtml view like this.
<html>
<body>
@RenderBody()
</body>
<script type="text/javascript" src="~/lib/layout.js"></script>
@RenderSection("scripts", required: false)
</html>
2. You have Contacts.cshtml.
@section Scripts{
<script type="text/javascript" src="~/lib/contacts.js"></script>
}
<div class="row">
<div class="col-md-6 col-md-offset-3">
<h2> Contacts</h2>
</div>
</div>
3. You have About.cshtml.
<div class="row">
<div class="col-md-6 col-md-offset-3">
<h2> Contacts</h2>
</div>
</div>
On your layout page, if required is set to false: @RenderSection("scripts", required: false), when the page renders and the user is on the about page, contacts.js won’t render.
<html>
<body><div>About<div>
</body>
<script type="text/javascript" src="~/lib/layout.js"></script>
</html>
If required is set to true: @RenderSection("scripts", required: true), When page renders and user is on the About page, contacts.js still gets rendered.
<html>
<body><div>About<div>
</body>
<script type="text/javascript" src="~/lib/layout.js"></script>
<script type="text/javascript" src="~/lib/contacts.js"></script>
</html>
IN SHORT, when set to true, whether you need it or not on other pages, it will get rendered anyhow. If set to false, it will render only when the child page is rendered.
