Strings

Strings are sequences of characters (specifically Unicode code points). Sass supports two kinds of strings whose internal structure is the same but which are rendered differently: quoted strings, like "Helvetica Neue", and unquoted strings (also known as identifiers), like bold. Together, these cover the different kinds of text that appear in CSS.

Escapes

All Sass strings support the standard CSS escape codes:

  • Any character other than a letter from A to F or a number from 0 to 9 (even a newline!) can be included as part of a string by writing \ in front of it.

  • Any character can be included as part of a string by writing \ followed by its Unicode code point number written in hexadecimal. You can optionally include a space after the code point number to indicate where the Unicode number ends.

SCSS Syntax

@debug "\""; // '"'
@debug \.widget; // \.widget
@debug "\a"; // "\a" (a string containing only a newline)
@debug "line1\a line2"; // "line1\a line2"
@debug "Nat + Liz \1F46D"; // "Nat + Liz 👭"

Sass Syntax

@debug "\""  // '"'
@debug \.widget  // \.widget
@debug "\a"  // "\a" (a string containing only a newline)
@debug "line1\a line2"  // "line1\a line2" (foo and bar are separated by a newline)
@debug "Nat + Liz \1F46D"  // "Nat + Liz 👭"

Quoted

Quoted strings are written between either single or double quotes, as in "Helvetica Neue". They can contain interpolation, as well as any unescaped character except for:

  • \, which can be escaped as \\;
  • ' or ", whichever was used to define that string, which can be escaped as \' or \";
  • newlines, which can be escaped as \a (including a trailing space).

Quoted strings are guaranteed to be compiled to CSS strings that have the same contents as the original Sass strings. The exact format may vary based on the implementation or configuration—a string containing a double quote may be compiled to "\"" or '"', and a non-ASCII character may or may not be escaped. But that should be parsed the same in any standards-compliant CSS implementation, including all browsers.

SCSS Syntax

@debug "Helvetica Neue"; // "Helvetica Neue"
@debug "C:\\Program Files"; // "C:\\Program Files"
@debug "\"Don't Fear the Reaper\""; // "\"Don't Fear the Reaper\""
@debug "line1\a line2"; // "line1\a line2"

$roboto-variant: "Mono";
@debug "Roboto #{$roboto-variant}"; // "Roboto Mono"

Sass Syntax

@debug "Helvetica Neue"  // "Helvetica Neue"
@debug "C:\\Program Files"  // "C:\\Program Files"
@debug "\"Don't Fear the Reaper\""  // "\"Don't Fear the Reaper\""
@debug "line1\a line2"  // "line1\a line2"

$roboto-variant: "Mono"
@debug "Roboto #{$roboto-variant}"  // "Roboto Mono"

Unquoted

Unquoted strings are written as CSS identifiers, following the syntax diagram below. They may include interpolation anywhere.

SCSS Syntax

@debug bold; // bold
@debug -webkit-flex; // -webkit-flex
@debug --123; // --123

$prefix: ms;
@debug -#{$prefix}-flex; // -ms-flex

Sass Syntax

@debug bold  // bold
@debug -webkit-flex  // -webkit-flex
@debug --123  // --123

$prefix: ms
@debug -#{$prefix}-flex  // -ms-flex

Escapes

Compatibility (Normalization):
Dart Sass
since 1.11.0
LibSass
Ruby Sass

LibSass, Ruby Sass, and older versions of Dart Sass don’t normalize escapes in identifiers. Instead, the text in the unquoted string is the exact text the user wrote. For example, \1F46D and 👭 are not considered equivalent.

When an unquoted string is parsed, the literal text of escapes are parsed as part of the string. For example, \a is parsed as the characters \, a, and space. In order to ensure that unquoted strings that have the same meanings in CSS are parsed the same way, though, these escapes are normalized. For each code point, whether it’s escaped or unescaped:

  • If it’s a valid identifier character, it’s included unescaped in the unquoted string. For example, \1F46D returns the unquoted string 👭.

  • If it’s a printable character other than a newline or a tab, it’s included after a \. For example, \21 returns the unquoted string \!.

  • Otherwise, the lowercase Unicode escape is included with a trailing space. For example, \7Fx returns the unquoted string \7f x.

SCSS Syntax

@debug \1F46D; // 👭
@debug \21; // \!
@debug \7Fx; // \7f x
@debug str-length(\7Fx); // 5

Sass Syntax

@debug \1F46D  // 👭
@debug \21  // \!
@debug \7Fx  // \7f x
@debug str-length(\7Fx)  // 5

String Indexes

Sass has a number of string functions that take or return numbers, called indexes, that refer to the characters in a string. The index 1 indicates the first character of the string. Note that this is different than many programming languages where indexes start at 0! Sass also makes it easy to refer to the end of a string. The index -1 refers to the last character in a string, -2 refers to the second-to-last, and so on.

SCSS Syntax

@debug str-index("Helvetica Neue", "Helvetica"); // 1
@debug str-index("Helvetica Neue", "Neue"); // 11
@debug str-slice("Roboto Mono", -4); // "Mono"

Sass Syntax

@debug str-index("Helvetica Neue", "Helvetica")  // 1
@debug str-index("Helvetica Neue", "Neue")  // 11
@debug str-slice("Roboto Mono", -4)  // "Mono"