Update index.js (#25)

Allows for `settings.sassOptions.data` field to be specified

Author: Gameghostify

index.js

@@ -1,5 +1,5 @@
-const sass = require('node-sass')
-const path = require('path')
+const sass = require('node-sass');
+const path = require('path');
 
 module.exports = (css, settings) => {
   const cssWithPlaceholders = css
@@ -12,14 +12,23 @@ module.exports = (css, settings) => {
 
   // Add the directory containing the current file to includePaths to enable relative
   // imports, only works when the filename is provided
-  const includePaths = settings.sassOptions && settings.sassOptions.includePaths || []
+  const includePaths = settings.sassOptions && settings.sassOptions.includePaths || [];
+  
   if (settings.babel && settings.babel.filename) {
     includePaths.push(path.dirname(settings.babel.filename));
   }
 
-  const preprocessed = sass.renderSync(Object.assign({
-    data: cssWithPlaceholders
-  }, settings.sassOptions, { includePaths })).css.toString()
+  // Prepend option data to cssWithPlaceholders
+  const optionData = settings.sassOptions && settings.sassOptions.data || "";
+  const data = optionData + "\n" + cssWithPlaceholders;
+
+  const preprocessed = sass.renderSync(
+    Object.assign(
+      {},
+      settings.sassOptions,
+      { data },
+      { includePaths }
+    )).css.toString()
 
   return preprocessed
     .replace(/styled-jsx-placeholder-(\d+)-(\w*\s*[),;!{])/g, (_, id, p1) =>