lib: refactor crypto cipher/hash/curve getters

* refactor internal util.filterDuplicateStrings() to eliminate unused
  code paths
* `.indexOf()` -> `.includes()` in test
* more concise arrow functions

PR-URL: https://github.com/nodejs/node/pull/10682
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michal Zasso <targos@protonmail.com>

lib/crypto.js

@@ -637,17 +637,17 @@ exports.randomBytes = exports.pseudoRandomBytes = randomBytes;
 
 exports.rng = exports.prng = randomBytes;
 
-exports.getCiphers = internalUtil.cachedResult(() => {
-  return internalUtil.filterDuplicateStrings(getCiphers());
-});
+exports.getCiphers = internalUtil.cachedResult(
+  () => internalUtil.filterDuplicateStrings(getCiphers())
+);
 
-exports.getHashes = internalUtil.cachedResult(() => {
-  return internalUtil.filterDuplicateStrings(getHashes());
-});
+exports.getHashes = internalUtil.cachedResult(
+  () => internalUtil.filterDuplicateStrings(getHashes())
+);
 
-exports.getCurves = internalUtil.cachedResult(() => {
-  return internalUtil.filterDuplicateStrings(getCurves());
-});
+exports.getCurves = internalUtil.cachedResult(
+  () => internalUtil.filterDuplicateStrings(getCurves())
+);
 
 Object.defineProperty(exports, 'fips', {
   get: getFipsCrypto,

lib/internal/util.js

@@ -134,20 +134,14 @@ exports.normalizeEncoding = function normalizeEncoding(enc) {
 // Filters duplicate strings. Used to support functions in crypto and tls
 // modules. Implemented specifically to maintain existing behaviors in each.
 exports.filterDuplicateStrings = function filterDuplicateStrings(items, low) {
-  if (!Array.isArray(items))
-    return [];
-  const len = items.length;
-  if (len <= 1)
-    return items;
   const map = new Map();
-  for (var i = 0; i < len; i++) {
+  for (var i = 0; i < items.length; i++) {
     const item = items[i];
     const key = item.toLowerCase();
     if (low) {
       map.set(key, key);
     } else {
-      if (!map.has(key) || map.get(key) <= item)
-        map.set(key, item);
+      map.set(key, item);
     }
   }
   return Array.from(map.values()).sort();

test/parallel/test-crypto-authenticated.js

@@ -312,7 +312,7 @@ const ciphers = crypto.getCiphers();
 for (const i in TEST_CASES) {
   const test = TEST_CASES[i];
 
-  if (ciphers.indexOf(test.algo) === -1) {
+  if (!ciphers.includes(test.algo)) {
     common.skip('unsupported ' + test.algo + ' test');
     continue;
   }