module: replace "magic" numbers by constants

- add new constants
- replace numbers by constants

PR-URL: #18869
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Matheus Marchini <matheus@sthima.com>

lib/internal/constants.js

@@ -14,6 +14,10 @@ module.exports = {
   CHAR_COLON: 58, /* : */
   CHAR_QUESTION_MARK: 63, /* ? */
   CHAR_UNDERSCORE: 95, /* _ */
+  CHAR_LINE_FEED: 10, /* \n */
+  CHAR_CARRIAGE_RETURN: 13, /* \r */
+  CHAR_EXCLAMATION_MARK: 33, /* ! */
+  CHAR_HASH: 35, /* # */
 
   // Digits
   CHAR_0: 48, /* 0 */

lib/internal/module.js

@@ -2,6 +2,13 @@
 
 const errors = require('internal/errors');
 
+const {
+  CHAR_LINE_FEED,
+  CHAR_CARRIAGE_RETURN,
+  CHAR_EXCLAMATION_MARK,
+  CHAR_HASH,
+} = require('internal/constants');
+
 // Invoke with makeRequireFunction(module) where |module| is the Module object
 // to use as the context for the require() function.
 function makeRequireFunction(mod) {
@@ -65,8 +72,8 @@ function stripShebang(content) {
   // Remove shebang
   var contLen = content.length;
   if (contLen >= 2) {
-    if (content.charCodeAt(0) === 35/*#*/ &&
-        content.charCodeAt(1) === 33/*!*/) {
+    if (content.charCodeAt(0) === CHAR_HASH &&
+        content.charCodeAt(1) === CHAR_EXCLAMATION_MARK) {
       if (contLen === 2) {
         // Exact match
         content = '';
@@ -75,7 +82,7 @@ function stripShebang(content) {
         var i = 2;
         for (; i < contLen; ++i) {
           var code = content.charCodeAt(i);
-          if (code === 10/*\n*/ || code === 13/*\r*/)
+          if (code === CHAR_LINE_FEED || code === CHAR_CARRIAGE_RETURN)
             break;
         }
         if (i === contLen)