Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.14)
// Compass (v1.0.3)
// ----

@function prepend-slash($value) {
  @return unquote('"\\#{$value}"');
}

// calling `prepend-slash` is only necessary when using a variable

$var-valid0: "f000";
$var-valid1: \f000;
$var-invalid: "\f000";

.valid0:before {
  content: prepend-slash($var-valid0);
}

.valid1:before {
  content: $var-valid1;
}

.invalid:before {
  content: $var-invalid;
}

.no-var:before {
  content: "\f000";
}

SassMeister-output.css

@charset "UTF-8";
.valid0:before {
  content: "\f000";
}

.valid1:before {
  content: \f000;
}

.invalid:before {
  content: "";
}

.no-var:before {
  content: "\f000";
}