Add support for detecting mp3 audio

index.js

@@ -16,7 +16,13 @@ module.exports.bufferCheck = input => {
         }, options);
 
         for (let i = 0; i < header.length; i++) {
-            if (header[i] !== buf[i + options.offset]) {
+            // If a bitmask is set
+            if (options.mask) {
+                // If header doesn't equal `buf` with bits masked off
+                if (header[i] !== (options.mask[i] & buf[i + options.offset])) {
+                    return false;
+                }
+            } else if (header[i] !== buf[i + options.offset]) {
                 return false;
             }
         }
@@ -51,6 +57,16 @@ module.exports.bufferCheck = input => {
         return typesList.wav;
     }
 
+    // Check for MPEG header at different starting offsets
+    for (let start = 0; start < 2 && start < (buf.length - 16); start++) {
+        if (
+            check([0x49, 0x44, 0x33], {offset: start}) || // ID3 header
+            check([0xFF, 0xE2], {offset: start, mask: [0xFF, 0xE2]}) // MPEG 1 or 2 Layer 3 header
+        ) {
+            return typesList.mp3;
+        }
+    }
+
     if (check([0x00, 0x00, 0x00, 0x0C, 0x6A, 0x50, 0x20,
         0x20, 0x0D, 0x0A, 0x87, 0x0A])) {
         // JPEG-2000 family

lib/typeslist.js

@@ -6,6 +6,7 @@ module.exports = {
     jp2: {ext: 'jpg', mime: 'image/jpg'},
     json: {ext: 'json', mime: 'application/json'},
     mj2: {ext: 'jpg', mime: 'image/jpg'},
+    mp3: {ext: 'mp3', mime: 'audio/mpeg'},
     png: {ext: 'png', mime: 'image/png'},
     webp: {ext: 'webp', mime: 'image/webp'},
     wav: {ext: 'wav', mime: 'audio/x-wav'},

test/unit/filetype.js

@@ -3,7 +3,7 @@ const fileType = require('../../index');
 const typesList = require('../../lib/typeslist');
 
 const checkList = [
-    'gif', 'jpg', 'json', 'png', 'wav', 'webp', 'zip'];
+    'gif', 'jpg', 'json', 'mp3', 'png', 'wav', 'webp', 'zip'];
 
 tap.test('check-types', t => {
     checkList.forEach(thisType => {