diff --git a/src/loader/m3u8-parser.js b/src/loader/m3u8-parser.js
index f499a9edafd..ab2b832221f 100644
--- a/src/loader/m3u8-parser.js
+++ b/src/loader/m3u8-parser.js
@@ -48,7 +48,8 @@ export default class M3U8Parser {
   }
 
   static convertAVC1ToAVCOTI (codec) {
-    let result, avcdata = codec.split('.');
+    let avcdata = codec.split('.');
+    let result;
     if (avcdata.length > 2) {
       result = avcdata.shift() + '.';
       result += parseInt(avcdata.shift()).toString(16);
@@ -64,7 +65,7 @@ export default class M3U8Parser {
   }
 
   static parseMasterPlaylist (string, baseurl) {
-    let levels = [], result;
+    let levels = [];
     MASTER_PLAYLIST_REGEX.lastIndex = 0;
 
     function setCodecs (codecs, level) {
@@ -84,6 +85,7 @@ export default class M3U8Parser {
       level.unknownCodecs = codecs;
     }
 
+    let result;
     while ((result = MASTER_PLAYLIST_REGEX.exec(string)) != null) {
       const level = {};
 
@@ -206,7 +208,7 @@ export default class M3U8Parser {
       } else {
         result = result[0].match(LEVEL_PLAYLIST_REGEX_SLOW);
         for (i = 1; i < result.length; i++) {
-          if (result[i] !== undefined) {
+          if (typeof result[i] !== 'undefined') {
             break;
           }
         }
@@ -243,13 +245,14 @@ export default class M3U8Parser {
         case 'DISCONTINUITY-SEQ':
           cc = parseInt(value1);
           break;
-        case 'KEY':
+        case 'KEY': {
           // https://tools.ietf.org/html/draft-pantos-http-live-streaming-08#section-3.4.4
-          var decryptparams = value1;
-          var keyAttrs = new AttrList(decryptparams);
-          var decryptmethod = keyAttrs.enumeratedString('METHOD'),
-            decrypturi = keyAttrs.URI,
-            decryptiv = keyAttrs.hexadecimalInteger('IV');
+          const decryptparams = value1;
+          const keyAttrs = new AttrList(decryptparams);
+          const decryptmethod = keyAttrs.enumeratedString('METHOD');
+          const decrypturi = keyAttrs.URI;
+          const decryptiv = keyAttrs.hexadecimalInteger('IV');
+
           if (decryptmethod) {
             levelkey = new LevelKey();
             if ((decrypturi) && (['AES-128', 'SAMPLE-AES', 'SAMPLE-AES-CENC'].indexOf(decryptmethod) >= 0)) {
@@ -263,18 +266,18 @@ export default class M3U8Parser {
             }
           }
           break;
-        case 'START':
-          let startParams = value1;
-          let startAttrs = new AttrList(startParams);
-          let startTimeOffset = startAttrs.decimalFloatingPoint('TIME-OFFSET');
+        }
+        case 'START': {
+          const startAttrs = new AttrList(value1);
+          const startTimeOffset = startAttrs.decimalFloatingPoint('TIME-OFFSET');
           // TIME-OFFSET can be 0
           if (Number.isFinite(startTimeOffset)) {
             level.startTimeOffset = startTimeOffset;
           }
-
           break;
-        case 'MAP':
-          let mapAttrs = new AttrList(value1);
+        }
+        case 'MAP': {
+          const mapAttrs = new AttrList(value1);
           frag.relurl = mapAttrs.URI;
           frag.rawByteRange = mapAttrs.BYTERANGE;
           frag.baseurl = baseurl;
@@ -285,6 +288,7 @@ export default class M3U8Parser {
           frag = new Fragment();
           frag.rawProgramDateTime = level.initSegment.rawProgramDateTime;
           break;
+        }
         default:
           logger.warn(`line parsed but not handled: ${result}`);
           break;