Merge commit 'e509cac533600cf4fa8382c9cdab78ddd82db688'

docs/content/en/functions/compare/Default.md

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+---
+title: compare.Default
+linkTitle: default
+description: Allows setting a default value that can be returned if a first value is not set.
+categories: [functions]
+keywords: []
+menu:
+  docs:
+    parent: functions
+function:
+  aliases: [default]
+  returnType: any
+  signatures: [compare.Default DEFAULT INPUT]
+relatedFunctions:
+  - compare.Conditional
+  - compare.Default
+aliases: [/functions/default]
+---
+
+`default` checks whether a given value is set and returns a default value if it is not. *Set* in this context means different things depending on the data type:
+
+* non-zero for numeric types and times
+* non-zero length for strings, arrays, slices, and maps
+* any boolean or struct value
+* non-nil for any other types
+
+`default` function examples reference the following content page:
+
+{{< code file="content/posts/default-function-example.md" >}}
+---
+title: Sane Defaults
+seo_title:
+date: 2017-02-18
+font:
+oldparam: The default function helps make your templating DRYer.
+newparam:
+---
+{{< /code >}}
+
+`default` can be written in more than one way:
+
+```go-html-template
+{{ .Params.font | default "Roboto" }}
+{{ default "Roboto" .Params.font }}
+```
+
+Both of the above `default` function calls return `Roboto`.
+
+A `default` value, however, does not need to be hard coded like the previous example. The `default` value can be a variable or pulled directly from the front matter using dot notation:
+
+```go-html-template
+{{ $old := .Params.oldparam }}
+<p>{{ .Params.newparam | default $old }}</p>
+```
+
+Which would return:
+
+```html
+<p>The default function helps make your templating DRYer.</p>
+```
+
+And then using dot notation
+
+```go-html-template
+<title>{{ .Params.seo_title | default .Title }}</title>
+```
+
+Which would return
+
+```html
+<title>Sane Defaults</title>
+```
+
+The following have equivalent return values but are far less terse. This demonstrates the utility of `default`:
+
+Using `if`:
+
+```go-html-template
+<title>{{ if .Params.seo_title }}{{ .Params.seo_title }}{{ else }}{{ .Title }}{{ end }}</title>
+=> Sane Defaults
+```
+
+Using `with`:
+
+```go-html-template
+<title>{{ with .Params.seo_title }}{{ . }}{{ else }}{{ .Title }}{{ end }}</title>
+=> Sane Defaults
+```