diff --git a/.eslintrc.js b/.eslintrc.js
index 348682e98d..86ec975d87 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -100,6 +100,7 @@ module.exports = {
     'prefer-promise-reject-errors': 'error',
     'prefer-rest-params': 'error',
     'prefer-spread': 'error',
+    'no-else-return': 'error',
   },
   settings: {
     react: {
diff --git a/src/actions/zipped-profiles.js b/src/actions/zipped-profiles.js
index 3978188ff2..ee74ea211b 100644
--- a/src/actions/zipped-profiles.js
+++ b/src/actions/zipped-profiles.js
@@ -91,9 +91,8 @@ export function viewProfileFromPathInZipFile(
     if (zipFileIndex === -1) {
       dispatch(showErrorForNoFileInZip(pathInZipFile));
       return Promise.resolve();
-    } else {
-      return dispatch(viewProfileFromZip(zipFileIndex));
     }
+    return dispatch(viewProfileFromZip(zipFileIndex));
   };
 }
 
diff --git a/src/components/shared/MarkerTooltipContents.js b/src/components/shared/MarkerTooltipContents.js
index 393e8d7103..21f791b0de 100644
--- a/src/components/shared/MarkerTooltipContents.js
+++ b/src/components/shared/MarkerTooltipContents.js
@@ -629,61 +629,56 @@ function getMarkerDetails(
               )}
             </div>
           );
-        } else {
-          return (
-            <div className="tooltipDetails">
-              {_markerDetail('status', 'Status', data.status)}
-              {_markerDetailNullable('url', 'URL', data.URI)}
-              {_markerDetailNullable(
-                'redirect_url',
-                'Redirect URL',
-                data.RedirectURI
-              )}
-              {_markerDetail('pri', 'Priority', data.pri)}
-              {_markerDetailBytesNullable(
-                'count',
-                'Requested bytes',
-                data.count
-              )}
-              {_markerDetailDeltaTimeNullable(
-                'domainLookup',
-                'Domain lookup in total',
-                data.domainLookupEnd,
-                data.domainLookupStart
-              )}
-              {_markerDetailDeltaTimeNullable(
-                'connect',
-                'Connection in total',
-                data.connectEnd,
-                data.connectStart
-              )}
-              {_markerDetailDeltaTimeNullable(
-                'tcpConnect',
-                'TCP connection in total',
-                data.tcpConnectEnd,
-                data.connectStart
-              )}
-              {_markerDetailDeltaTimeNullable(
-                'secureConnectionStart',
-                'Start of secure connection at',
-                data.secureConnectionStart,
-                data.tcpConnectEnd
-              )}
-              {_markerDetailDeltaTimeNullable(
-                'requestStart',
-                'Start of request at',
-                data.requestStart,
-                data.connectStart
-              )}
-              {_markerDetailDeltaTimeNullable(
-                'response',
-                'Response time',
-                data.responseEnd,
-                data.responseStart
-              )}
-            </div>
-          );
         }
+        return (
+          <div className="tooltipDetails">
+            {_markerDetail('status', 'Status', data.status)}
+            {_markerDetailNullable('url', 'URL', data.URI)}
+            {_markerDetailNullable(
+              'redirect_url',
+              'Redirect URL',
+              data.RedirectURI
+            )}
+            {_markerDetail('pri', 'Priority', data.pri)}
+            {_markerDetailBytesNullable('count', 'Requested bytes', data.count)}
+            {_markerDetailDeltaTimeNullable(
+              'domainLookup',
+              'Domain lookup in total',
+              data.domainLookupEnd,
+              data.domainLookupStart
+            )}
+            {_markerDetailDeltaTimeNullable(
+              'connect',
+              'Connection in total',
+              data.connectEnd,
+              data.connectStart
+            )}
+            {_markerDetailDeltaTimeNullable(
+              'tcpConnect',
+              'TCP connection in total',
+              data.tcpConnectEnd,
+              data.connectStart
+            )}
+            {_markerDetailDeltaTimeNullable(
+              'secureConnectionStart',
+              'Start of secure connection at',
+              data.secureConnectionStart,
+              data.tcpConnectEnd
+            )}
+            {_markerDetailDeltaTimeNullable(
+              'requestStart',
+              'Start of request at',
+              data.requestStart,
+              data.connectStart
+            )}
+            {_markerDetailDeltaTimeNullable(
+              'response',
+              'Response time',
+              data.responseEnd,
+              data.responseStart
+            )}
+          </div>
+        );
       }
       case 'Styles': {
         return [
diff --git a/src/components/timeline/TrackContextMenu.js b/src/components/timeline/TrackContextMenu.js
index a9fad96ffa..3794452db5 100644
--- a/src/components/timeline/TrackContextMenu.js
+++ b/src/components/timeline/TrackContextMenu.js
@@ -213,14 +213,13 @@ class TimelineTrackContextMenu extends PureComponent<Props> {
 
     if (rightClickedTrack.type === 'global') {
       return globalTrackNames[rightClickedTrack.trackIndex];
-    } else {
-      const localTrackNames = localTrackNamesByPid.get(rightClickedTrack.pid);
-      if (localTrackNames === undefined) {
-        console.error('Expected to find a local track name for the given pid.');
-        return 'Unknown Track';
-      }
-      return localTrackNames[rightClickedTrack.trackIndex];
     }
+    const localTrackNames = localTrackNamesByPid.get(rightClickedTrack.pid);
+    if (localTrackNames === undefined) {
+      console.error('Expected to find a local track name for the given pid.');
+      return 'Unknown Track';
+    }
+    return localTrackNames[rightClickedTrack.trackIndex];
   }
 
   renderIsolateProcess() {
diff --git a/src/profile-logic/convert-markers.js b/src/profile-logic/convert-markers.js
index 7a926d10c7..f45f203505 100644
--- a/src/profile-logic/convert-markers.js
+++ b/src/profile-logic/convert-markers.js
@@ -19,8 +19,8 @@ export function upgradeGCMinorMarker(marker8: Object): GCMinorMarkerPayload {
         marker8.nursery.status = 'nursery empty';
       }
       return Object.assign(marker8);
-    } else {
-      /*
+    }
+    /*
        * This is the old format for GCMinor, rename some
        * properties to the more sensible names in the newer
        * format and set the status.
@@ -29,23 +29,21 @@ export function upgradeGCMinorMarker(marker8: Object): GCMinorMarkerPayload {
        * promotion_rate, leave them so that anyone opening the
        * raw json data can still see them in converted profiles.
        */
-      const marker = Object.assign(marker8, {
-        nursery: Object.assign(marker8.nursery, {
-          status: 'complete',
-          bytes_used: marker8.nursery.nursery_bytes,
-          // cur_capacity cannot be filled in.
-          new_capacity: marker8.nursery.new_nursery_bytes,
-          phase_times: marker8.nursery.timings,
-        }),
-      });
-      delete marker.nursery.nursery_bytes;
-      delete marker.nursery.new_nursery_bytes;
-      delete marker.nursery.timings;
-      return marker;
-    }
-  } else {
-    return marker8;
+    const marker = Object.assign(marker8, {
+      nursery: Object.assign(marker8.nursery, {
+        status: 'complete',
+        bytes_used: marker8.nursery.nursery_bytes,
+        // cur_capacity cannot be filled in.
+        new_capacity: marker8.nursery.new_nursery_bytes,
+        phase_times: marker8.nursery.timings,
+      }),
+    });
+    delete marker.nursery.nursery_bytes;
+    delete marker.nursery.new_nursery_bytes;
+    delete marker.nursery.timings;
+    return marker;
   }
+  return marker8;
 }
 
 /*
diff --git a/src/reducers/profile-view.js b/src/reducers/profile-view.js
index 78e2479413..3211f920e9 100644
--- a/src/reducers/profile-view.js
+++ b/src/reducers/profile-view.js
@@ -661,16 +661,15 @@ export const getRightClickedThreadIndex = createSelector(
     if (rightClickedTrack.type === 'global') {
       const track = globalTracks[rightClickedTrack.trackIndex];
       return track.type === 'process' ? track.mainThreadIndex : null;
-    } else {
-      const { pid, trackIndex } = rightClickedTrack;
-      const localTracks = ensureExists(
-        localTracksByPid.get(pid),
-        'No local tracks found at that pid.'
-      );
-      const track = localTracks[trackIndex];
-
-      return track.type === 'thread' ? track.threadIndex : null;
     }
+    const { pid, trackIndex } = rightClickedTrack;
+    const localTracks = ensureExists(
+      localTracksByPid.get(pid),
+      'No local tracks found at that pid.'
+    );
+    const track = localTracks[trackIndex];
+
+    return track.type === 'thread' ? track.threadIndex : null;
   }
 );
 export const getGlobalTrackNames = createSelector(
diff --git a/src/utils/format-numbers.js b/src/utils/format-numbers.js
index 6fcc164442..59c2dfd0d0 100644
--- a/src/utils/format-numbers.js
+++ b/src/utils/format-numbers.js
@@ -60,9 +60,8 @@ export function formatBytes(bytes: number): string {
     return formatNumber(bytes / 1024, 3, 2) + 'KB';
   } else if (bytes < 1024 * 1024 * 1024) {
     return formatNumber(bytes / (1024 * 1024), 3, 2) + 'MB';
-  } else {
-    return formatNumber(bytes / (1024 * 1024 * 1024), 3, 2) + 'GB';
   }
+  return formatNumber(bytes / (1024 * 1024 * 1024), 3, 2) + 'GB';
 }
 
 export function formatSI(num: number): string {
@@ -73,9 +72,8 @@ export function formatSI(num: number): string {
     return formatNumber(num / 1000, 3, 2) + 'K';
   } else if (num < 1000 * 1000 * 1000) {
     return formatNumber(num / (1000 * 1000), 3, 2) + 'M';
-  } else {
-    return formatNumber(num / (1000 * 1000 * 1000), 3, 2) + 'G';
   }
+  return formatNumber(num / (1000 * 1000 * 1000), 3, 2) + 'G';
 }
 
 export function formatMicroseconds(