refactor(server): refactoring of watcher (#3173)

lib/watcher.js

@@ -26,7 +26,7 @@ function watchPatterns (patterns, watcher) {
   pathsToWatch = Array.from(pathsToWatch)
   // watch only common parents, no sub paths
   pathsToWatch.forEach((path) => {
-    if (!pathsToWatch.some((p) => p !== path && path.substr(0, p.length + 1) === p + DIR_SEP)) {
+    if (!pathsToWatch.some((p) => p !== path && path.startsWith(p + DIR_SEP))) {
       watcher.add(path)
       log.debug('Watching "%s"', path)
     }
@@ -39,22 +39,18 @@ function checkAnyPathMatch (patterns, path) {
 
 function createIgnore (patterns, excludes) {
   return function (path, stat) {
-    if (!stat || stat.isDirectory()) {
+    if (stat && !stat.isDirectory()) {
+      return !checkAnyPathMatch(patterns, path) || checkAnyPathMatch(excludes, path)
+    } else {
       return false
     }
-
-    return !checkAnyPathMatch(patterns, path) || checkAnyPathMatch(excludes, path)
   }
 }
 
 function getWatchedPatterns (patterns) {
   return patterns
-    .reduce((array, pattern) => {
-      if (pattern.watched) {
-        array.push(pattern.pattern)
-      }
-      return array
-    }, [])
+    .filter((pattern) => pattern.watched)
+    .map((pattern) => pattern.pattern)
 }
 
 exports.watch = function (patterns, excludes, fileList, usePolling, emitter) {