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

     1  ---
     2  title: findRE
     3  description: Returns a list of strings that match the regular expression.
     4  godocref:
     5  date: 2017-02-01
     6  publishdate: 2017-02-01
     7  lastmod: 2017-02-01
     8  categories: [functions]
     9  menu:
    10    docs:
    11      parent: "functions"
    12  keywords: [regex]
    13  signature: ["findRE PATTERN INPUT [LIMIT]"]
    14  workson: []
    15  hugoversion:
    16  relatedfuncs: []
    17  deprecated: false
    18  aliases: []
    19  ---
    20  
    21  
    22  By default all matches will be included. The number of matches can be limitted with an optional third parameter.
    23  
    24  The example below returns a list of all second level headers (`<h2>`) in the content:
    25  
    26  ```
    27  {{ findRE "<h2.*?>(.|\n)*?</h2>" .Content }}
    28  ```
    29  
    30  You can limit the number of matches in the list with a third parameter. The following example shows how to limit the returned value to just one match (or none, if there are no matched substrings):
    31  
    32  ```
    33  {{ findRE "<h2.*?>(.|\n)*?</h2>" .Content 1 }}
    34      <!-- returns ["<h2 id="#foo">Foo</h2>"] -->
    35  ```
    36  
    37  {{% note %}}
    38  Hugo uses Go's [Regular Expression package](https://golang.org/pkg/regexp/), which is the same general syntax used by Perl, Python, and other languages but with a few minor differences for those coming from a background in PCRE. For a full syntax listing, see the [GitHub wiki for re2](https://github.com/google/re2/wiki/Syntax).
    39  
    40  If you are just learning RegEx, or at least Go's flavor, you can practice pattern matching in the browser at <https://regex101.com/>.
    41  {{% /note %}}
    42  
    43  
    44  [partials]: /templates/partials/
    45  [`plainify`]: /functions/plainify/
    46  [toc]: /content-management/toc/
    47  [`urlize`]: /functions/urlize