.Dd April 5, 2016
.Dt he 1
.Sh NAME
.Nm he
.Nd encode/decode HTML entities just like a browser would
.Sh SYNOPSIS
.Nm
.Op Fl -escape Ar string
.br
.Op Fl -encode Ar string
.br
.Op Fl -encode Fl -use-named-refs Fl -everything Fl -allow-unsafe Ar string
.br
.Op Fl -decode Ar string
.br
.Op Fl -decode Fl -attribute Ar string
.br
.Op Fl -decode Fl -strict Ar string
.br
.Op Fl v | -version
.br
.Op Fl h | -help
.Sh DESCRIPTION
.Nm
encodes/decodes HTML entities in strings just like a browser would.
.Sh OPTIONS
.Bl -ohang -offset
.It Sy "--escape"
Take a string of text and escape it for use in text contexts in XML or HTML documents. Only the following characters are escaped: `&`, `<`, `>`, `"`, and `'`.
.It Sy "--encode"
Take a string of text and encode any symbols that aren't printable ASCII symbols and that can be replaced with character references. For example, it would turn `©` into `&#xA9;`, but it wouldn't turn `+` into `&#x2B;` since there is no point in doing so. Additionally, it replaces any remaining non-ASCII symbols with a hexadecimal escape sequence (e.g. `&#x1D306;`). The return value of this function is always valid HTML.
.It Sy "--encode --use-named-refs"
Enable the use of named character references (like `&copy;`) in the output. If compatibility with older browsers is a concern, don't use this option.
.It Sy "--encode --everything"
Encode every symbol in the input string, even safe printable ASCII symbols.
.It Sy "--encode --allow-unsafe"
Encode non-ASCII characters only. This leaves unsafe HTML/XML symbols like `&`, `<`, `>`, `"`, and `'` intact.
.It Sy "--encode --decimal"
Use decimal digits rather than hexadecimal digits for encoded character references, e.g. output `&#169;` instead of `&#xA9;`.
.It Sy "--decode"
Takes a string of HTML and decode any named and numerical character references in it using the algorithm described in the HTML spec.
.It Sy "--decode --attribute"
Parse the input as if it was an HTML attribute value rather than a string in an HTML text content.
.It Sy "--decode --strict"
Throw an error if an invalid character reference is encountered.
.It Sy "-v, --version"
Print he's version.
.It Sy "-h, --help"
Show the help screen.
.El
.Sh EXIT STATUS
The
.Nm he
utility exits with one of the following values:
.Pp
.Bl -tag -width flag -compact
.It Li 0
.Nm
did what it was instructed to do successfully; either it encoded/decoded the input and printed the result, or it printed the version or usage message.
.It Li 1
.Nm
encountered an error.
.El
.Sh EXAMPLES
.Bl -ohang -offset
.It Sy "he --escape '<script>alert(1)</script>'"
Print an escaped version of the given string that is safe for use in HTML text contexts, escaping only `&`, `<`, `>`, `"`, and `'`.
.It Sy "he --decode '&copy;&#x1D306;'"
Print the decoded version of the given HTML string.
.It Sy "echo\ '&copy;&#x1D306;'\ |\ he --decode"
Print the decoded version of the HTML string that gets piped in.
.El
.Sh BUGS
he's bug tracker is located at <https://github.com/mathiasbynens/he/issues>.
.Sh AUTHOR
Mathias Bynens <https://mathiasbynens.be/>
.Sh WWW
<https://mths.be/he>