Clarify .Page.Param method (#1953)

content/en/functions/param.md

@@ -1,40 +1,47 @@
 ---
 title: .Param
-description: Calls page or site variables into your template.
-date: 2017-02-01
-publishdate: 2017-02-01
-lastmod: 2017-04-30
-keywords: ["front matter"]
+description: Returns a page parameter, falling back to a site parameter if present.
+signature: ['.Param KEY']
 categories: [functions]
+keywords: ['front matter', 'params']
 menu:
   docs:
-    parent: "functions"
-toc:
-signature: [".Param KEY"]
-workson: []
-hugoversion:
-relatedfuncs: [default]
-deprecated: false
-draft: false
+    parent: 'functions'
 aliases: []
 ---
 
-In Hugo, you can declare [site-wide params][sitevars] (i.e. in your [configuration]), as well as params for [individual pages][pagevars].
+The `.Param` method on `.Page` looks for the given `KEY` in page parameters, and returns the corresponding value. If it cannot find the `KEY` in page parameters, it looks for the `KEY` in site parameters. If it cannot find the `KEY` in either location, the `.Param` method returns `nil`. 
 
-A common use case is to have a general value for the site and a more specific value for some of the pages (e.g., an image).
+Site and theme developers commonly set parameters at the site level, allowing content authors to override those parameters at the page level.
 
-You can use the `.Param` method to call these values into your template. The following will first look for an `image` param in a specific content's [front matter]. If not found, Hugo will look for an `image` param in your site's configuration:
+For example, to show a table of contents on every page, but allow authors to hide the table of contents as needed:
 
-```
-$.Param "image"
-```
+**Configuration**
 
-{{% note %}}
-The `Param` method may not consider empty strings in a content's front matter as "not found." If you are setting preconfigured front matter fields to empty strings using Hugo's archetypes, it may be best to use the [`default` function](/functions/default/) instead of `Param`. See the [related issue on GitHub](https://github.com/gohugoio/hugo/issues/3366).
-{{% /note %}}
+{{< code-toggle file="config" copy=false >}}
+[params]
+display_toc = true
+{{< /code-toggle >}}
 
+**Content**
 
-[configuration]: /getting-started/configuration/
-[front matter]: /content-management/front-matter/
-[pagevars]: /variables/page/
-[sitevars]: /variables/site/
+{{< code-toggle file="content/about.md" fm=true copy=false >}}
+title = 'About'
+date = 2023-01-01
+draft = false
+display_toc = false
+{{< /code-toggle >}}
+
+**Template**
+
+{{< code file="layouts/_default/single.html" copy="false" >}}
+{{ if .Param "display_toc" }}
+  {{ .TableOfContents }}
+{{ end }}
+{{< /code >}}
+
+The `.Param` method returns the value associated with the given `KEY`, regardless of whether the value is truthy or falsy. If you need to ignore falsy values, use this construct instead:
+
+{{< code file="layouts/_default/single.html" copy="false" >}}
+{{ or .Params.foo site.Params.foo }}
+{{< /code >}}