os: lazy loaded

BridgeAR · MylesBorins · commit 28d00a18c8db · 2018-05-22T14:13:28.000-04:00
PR-URL: #20567 Reviewed-By: Gus Caplan <me@gus.host> Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
diff --git a/lib/assert.js b/lib/assert.js
@@ -33,7 +33,7 @@ const { codes: {
 const { AssertionError, errorCache } = require('internal/assert');
 const { openSync, closeSync, readSync } = require('fs');
 const { inspect, types: { isPromise, isRegExp } } = require('util');
-const { EOL } = require('os');
+const { EOL } = require('internal/constants');
 const { NativeModule } = require('internal/bootstrap/loaders');
 
 // Escape control characters but not \n and \t to keep the line breaks and
diff --git a/lib/internal/constants.js b/lib/internal/constants.js
@@ -1,5 +1,7 @@
 'use strict';
 
+const isWindows = process.platform === 'win32';
+
 module.exports = {
   // Alphabet chars.
   CHAR_UPPERCASE_A: 65, /* A */
@@ -45,4 +47,6 @@ module.exports = {
   // Digits
   CHAR_0: 48, /* 0 */
   CHAR_9: 57, /* 9 */
+
+  EOL: isWindows ? '\r\n' : '\n'
 };
diff --git a/lib/internal/tty.js b/lib/internal/tty.js
@@ -22,9 +22,7 @@
 
 'use strict';
 
-const { release } = require('os');
-
-const OSRelease = release().split('.');
+let OSRelease;
 
 const COLORS_2 = 1;
 const COLORS_16 = 4;
@@ -75,6 +73,11 @@ function getColorDepth(env = process.env) {
   }
 
   if (process.platform === 'win32') {
+    // Lazy load for startup performance.
+    if (OSRelease === undefined) {
+      const { release } = require('os');
+      OSRelease = release().split('.');
+    }
     // Windows 10 build 10586 is the first Windows release that supports 256
     // colors. Windows 10 build 14931 is the first release that supports
     // 16m/TrueColor.
