Using media types instead of filename extension

lib/css-b64-images.js

@@ -3,7 +3,20 @@ var fs = require('fs'),
   /* Adapted from https://gist.github.com/2594980 */
   imgRegex = /url\s?\(['"]?(.*?)(?=['"]?\))/gi,
   absoluteUrlRegex = /^\//,
-  externalUrlRegex = /http/;
+  externalUrlRegex = /http/,
+  mediatypes = {
+    'eot'       : 'application/vnd.ms-fontobject',
+    'gif'       : 'image/gif',
+    'ico'       : 'image/vnd.microsoft.icon',
+    'jpg'       : 'image/jpeg',
+    'jpeg'      : 'image/jpeg',
+    'otf'       : 'application/x-font-opentype',
+    'png'       : 'image/png',
+    'svg'       : 'image/svg+xml',
+    'ttf'       : 'application/x-font-ttf',
+    'webp'      : 'image/webp',
+    'woff'      : 'application/x-font-woff'
+  };
 
 module.exports = {
   fromFile: fromFile,
@@ -57,7 +70,7 @@ function replaceUrlByB64(imageUrl, imagePath, css, cb){
     fs.readFile(imagePath, 'base64', function(err, img){
       if(err) return cb(err, css);
       var ext = imagePath.substr(imagePath.lastIndexOf('.') + 1);
-      var newCss = css.replace(imageUrl, 'data:image/' + ext + ';base64,' + img);
+      var newCss = css.replace(imageUrl, 'data:' + mediatypes[ext] + ';base64,' + img);
       cb(null, newCss);
     });
   });

test/css-b64-images-test.js

@@ -33,4 +33,6 @@ function cssShouldBeCorrect(css){
   css.should.include(".external {\n  background: url('http");
   css.should.include(".tooBig {\n  background: url('../img");
   css.should.include(".not-found {\n  background: url('../img");
+
+  css.should.include(".mediatype {\n  background: url('data:image/svg+xml;base64,");
 }

test/fixture/css/style.css

@@ -46,3 +46,7 @@
 .not-found {
   background: url('../img/nlabal.png');
 }
+
+.mediatype {
+  background: url('../img/dots.svg');
+}