github.com/lyeb/hugo@v0.47.1/docs/content/en/functions/len.md (about)

     1  ---
     2  title: len
     3  linktitle: len
     4  description: Returns the length of a variable according to its type.
     5  godocref: https://golang.org/pkg/builtin/#len
     6  date: 2017-02-01
     7  publishdate: 2017-02-01
     8  lastmod: 2017-04-18
     9  categories: [functions]
    10  keywords: []
    11  signature: ["len INPUT"]
    12  workson: [lists,taxonomies,terms]
    13  hugoversion:
    14  relatedfuncs: []
    15  deprecated: false
    16  toc: false
    17  aliases: []
    18  ---
    19  
    20  `len` is a built-in function in Go that returns the length of a variable according to its type. From the Go documentation:
    21  
    22  > Array: the number of elements in v.
    23  >
    24  > Pointer to array: the number of elements in *v (even if v is nil).
    25  >
    26  > Slice, or map: the number of elements in v; if v is nil, len(v) is zero.
    27  >
    28  > String: the number of bytes in v.
    29  >
    30  > Channel: the number of elements queued (unread) in the channel buffer; if v is nil, len(v) is zero.
    31  
    32  `len` is also considered a [fundamental function for Hugo templating][].
    33  
    34  ## `len` Example 1: Longer Headings
    35  
    36  You may want to append a class to a heading according to the length of the string therein. The following templating checks to see if the title's length is greater than 80 characters and, if so, adds a `long-title` class to the `<h1>`:
    37  
    38  {{< code file="check-title-length.html" >}}
    39  <header>
    40      <h1{{if gt (len .Title) 80}} class="long-title"{{end}}>{{.Title}}</h1>
    41  </header>
    42  {{< /code >}}
    43  
    44  ## `len` Example 2: Counting Pages with `where`
    45  
    46  The following templating uses [`where`][] in conjunction with `len` to figure out the total number of content pages in a `posts` [section][]:
    47  
    48  {{< code file="how-many-posts.html" >}}
    49  {{ $posts := (where .Site.RegularPages "Section" "==" "post") }}
    50  {{ $postCount := len $posts }}
    51  {{< /code >}}
    52  
    53  Note the use of `.RegularPages`, a [site variable][] that counts all regular content pages but not the `_index.md` pages used to add front matter and content to [list templates][].
    54  
    55  
    56  [fundamental function for Hugo templating]: /templates/introduction/
    57  [list templates]: /templates/lists/
    58  [section]: /content-management/sections/
    59  [site variable]: /variables/site/
    60  [`where`]: /functions/where/