module: replace magic numbers by constants

- add new constants
- replace "magic" numbers in "module" by constants

PR-URL: #18785
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Matheus Marchini <matheus@sthima.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

Author: daynin

lib/internal/constants.js

@@ -2,15 +2,20 @@
 
 module.exports = {
   // Alphabet chars.
-  CHAR_UPPERCASE_A: 65, /*A*/
-  CHAR_LOWERCASE_A: 97, /*a*/
-  CHAR_UPPERCASE_Z: 90, /*Z*/
-  CHAR_LOWERCASE_Z: 122, /*z*/
+  CHAR_UPPERCASE_A: 65, /* A */
+  CHAR_LOWERCASE_A: 97, /* a */
+  CHAR_UPPERCASE_Z: 90, /* Z */
+  CHAR_LOWERCASE_Z: 122, /* z */
 
   // Non-alphabetic chars.
-  CHAR_DOT: 46, /*.*/
-  CHAR_FORWARD_SLASH: 47, /*/*/
-  CHAR_BACKWARD_SLASH: 92, /*\*/
-  CHAR_COLON: 58, /*:*/
-  CHAR_QUESTION_MARK: 63, /*?*/
+  CHAR_DOT: 46, /* . */
+  CHAR_FORWARD_SLASH: 47, /* / */
+  CHAR_BACKWARD_SLASH: 92, /* \ */
+  CHAR_COLON: 58, /* : */
+  CHAR_QUESTION_MARK: 63, /* ? */
+  CHAR_UNDERSCORE: 95, /* _ */
+
+  // Digits
+  CHAR_0: 48, /* 0 */
+  CHAR_9: 57, /* 9 */
 };

lib/module.js

@@ -47,6 +47,19 @@ module.exports = Module;
 const internalESModule = require('internal/process/modules');
 const ModuleJob = require('internal/loader/ModuleJob');
 const createDynamicModule = require('internal/loader/CreateDynamicModule');
+const {
+  CHAR_UPPERCASE_A,
+  CHAR_LOWERCASE_A,
+  CHAR_UPPERCASE_Z,
+  CHAR_LOWERCASE_Z,
+  CHAR_FORWARD_SLASH,
+  CHAR_BACKWARD_SLASH,
+  CHAR_COLON,
+  CHAR_DOT,
+  CHAR_UNDERSCORE,
+  CHAR_0,
+  CHAR_9,
+} = require('internal/constants');
 
 function stat(filename) {
   filename = path.toNamespacedPath(filename);
@@ -201,7 +214,7 @@ Module._findPath = function(request, paths, isMain) {
 
   var exts;
   var trailingSlash = request.length > 0 &&
-                      request.charCodeAt(request.length - 1) === 47/*/*/;
+    request.charCodeAt(request.length - 1) === CHAR_FORWARD_SLASH;
 
   // For each path
   for (var i = 0; i < paths.length; i++) {
@@ -276,8 +289,8 @@ if (process.platform === 'win32') {
 
     // return root node_modules when path is 'D:\\'.
     // path.resolve will make sure from.length >=3 in Windows.
-    if (from.charCodeAt(from.length - 1) === 92/*\*/ &&
-        from.charCodeAt(from.length - 2) === 58/*:*/)
+    if (from.charCodeAt(from.length - 1) === CHAR_BACKWARD_SLASH &&
+        from.charCodeAt(from.length - 2) === CHAR_COLON)
       return [from + 'node_modules'];
 
     const paths = [];
@@ -290,7 +303,9 @@ if (process.platform === 'win32') {
       // Use colon as an extra condition since we can get node_modules
       // path for drive root like 'C:\node_modules' and don't need to
       // parse drive name.
-      if (code === 92/*\*/ || code === 47/*/*/ || code === 58/*:*/) {
+      if (code === CHAR_BACKWARD_SLASH ||
+          code === CHAR_FORWARD_SLASH ||
+          code === CHAR_COLON) {
         if (p !== nmLen)
           paths.push(from.slice(0, last) + '\\node_modules');
         last = i;
@@ -324,7 +339,7 @@ if (process.platform === 'win32') {
     var last = from.length;
     for (var i = from.length - 1; i >= 0; --i) {
       const code = from.charCodeAt(i);
-      if (code === 47/*/*/) {
+      if (code === CHAR_FORWARD_SLASH) {
         if (p !== nmLen)
           paths.push(from.slice(0, last) + '/node_modules');
         last = i;
@@ -357,9 +372,9 @@ Module._resolveLookupPaths = function(request, parent, newReturn) {
 
   // Check for relative path
   if (request.length < 2 ||
-      request.charCodeAt(0) !== 46/*.*/ ||
-      (request.charCodeAt(1) !== 46/*.*/ &&
-       request.charCodeAt(1) !== 47/*/*/)) {
+      request.charCodeAt(0) !== CHAR_DOT ||
+      (request.charCodeAt(1) !== CHAR_DOT &&
+       request.charCodeAt(1) !== CHAR_FORWARD_SLASH)) {
     var paths = modulePaths;
     if (parent) {
       if (!parent.paths)
@@ -407,10 +422,10 @@ Module._resolveLookupPaths = function(request, parent, newReturn) {
       // We matched 'index.', let's validate the rest
       for (; i < base.length; ++i) {
         const code = base.charCodeAt(i);
-        if (code !== 95/*_*/ &&
-            (code < 48/*0*/ || code > 57/*9*/) &&
-            (code < 65/*A*/ || code > 90/*Z*/) &&
-            (code < 97/*a*/ || code > 122/*z*/))
+        if (code !== CHAR_UNDERSCORE &&
+            (code < CHAR_0 || code > CHAR_9) &&
+            (code < CHAR_UPPERCASE_A || code > CHAR_UPPERCASE_Z) &&
+            (code < CHAR_LOWERCASE_A || code > CHAR_LOWERCASE_Z))
           break;
       }
       if (i === base.length) {