safe.URL

Syntax

safe.URL INPUT ⟼ template.URL

Alias

safeURL

safeURL declares the provided string as a “safe” URL or URL substring (see RFC 3986). A URL like javascript:checkThatFormNotEditedBeforeLeavingPage() from a trusted source should go in the page, but by default dynamic javascript: URLs are filtered out since they are a frequently exploited injection vector.

Without safeURL, only the URI schemes http:, https: and mailto: are considered safe by Go templates. If any other URI schemes (e.g., irc: and javascript:) are detected, the whole URL will be replaced with #ZgotmplZ. This is to “defang” any potential attack in the URL by rendering it useless.

The following examples use a site hugo.toml with the following menu entry:

menu:
  main:
  - name: 'IRC: #golang at freenode'
    url: irc://irc.freenode.net/#golang

[menu]
[[menu.main]]
    name = 'IRC: #golang at freenode'
    url = 'irc://irc.freenode.net/#golang'

{
   "menu": {
      "main": [
         {
            "name": "IRC: #golang at freenode",
            "url": "irc://irc.freenode.net/#golang"
         }
      ]
   }
}

The following is an example of a sidebar partial that may be used in conjunction with the preceding front matter example:

<!-- This unordered list may be part of a sidebar menu -->
<ul>
  {{ range .Site.Menus.main }}
    <li><a href="{{ .URL }}">{{ .Name }}</a></li>
  {{ end }}
</ul>

This partial would produce the following HTML output:

<!-- This unordered list may be part of a sidebar menu -->
<ul>
  <li><a href="#ZgotmplZ">IRC: #golang at freenode</a></li>
</ul>

The odd output can be remedied by adding | safeURL to our .URL page variable:

<!-- This unordered list may be part of a sidebar menu -->
<ul>
    <li><a href="{{ .URL | safeURL }}">{{ .Name }}</a></li>
</ul>

With the .URL page variable piped through safeURL, we get the desired output:

<ul class="sidebar-menu">
  <li><a href="irc://irc.freenode.net/#golang">IRC: #golang at freenode</a></li>
</ul>