[Refactor] hoist regex expressions for efficiency (#336)

Author: mrjf

.eslintrc

@@ -14,7 +14,7 @@
         "func-style": 0,
         "global-require": 1,
         "id-length": [2, { "min": 1, "max": 40 }],
-        "max-lines": [2, 350],
+        "max-lines": [2, 360],
         "max-lines-per-function": 0,
         "max-nested-callbacks": 0,
         "max-params": 0,

lib/async.js

@@ -8,6 +8,10 @@ var isCore = require('is-core-module');
 
 var realpathFS = process.platform !== 'win32' && fs.realpath && typeof fs.realpath.native === 'function' ? fs.realpath.native : fs.realpath;
 
+var relativePathRegex = /^(?:\.\.?(?:\/|$)|\/|([A-Za-z]:)?[/\\])/;
+var windowsDriveRegex = /^\w:[/\\]*$/;
+var nodeModulesRegex = /[/\\]node_modules[/\\]*$/;
+
 var homedir = getHomedir();
 var defaultPaths = function () {
     return [
@@ -124,10 +128,10 @@ module.exports = function resolve(x, options, callback) {
 
     var res;
     function init(basedir) {
-        if ((/^(?:\.\.?(?:\/|$)|\/|([A-Za-z]:)?[/\\])/).test(x)) {
+        if (relativePathRegex.test(x)) {
             res = path.resolve(basedir, x);
             if (x === '.' || x === '..' || x.slice(-1) === '/') res += '/';
-            if ((/\/$/).test(x) && res === basedir) {
+            if (x.slice(-1) === '/' && res === basedir) {
                 loadAsDirectory(res, opts.package, onfile);
             } else loadAsFile(res, opts.package, onfile);
         } else if (includeCoreModules && isCore(x)) {
@@ -215,10 +219,10 @@ module.exports = function resolve(x, options, callback) {
 
     function loadpkg(dir, cb) {
         if (dir === '' || dir === '/') return cb(null);
-        if (process.platform === 'win32' && (/^\w:[/\\]*$/).test(dir)) {
+        if (process.platform === 'win32' && windowsDriveRegex.test(dir)) {
             return cb(null);
         }
-        if ((/[/\\]node_modules[/\\]*$/).test(dir)) return cb(null);
+        if (nodeModulesRegex.test(dir)) return cb(null);
 
         maybeRealpath(realpath, dir, opts, function (unwrapErr, pkgdir) {
             if (unwrapErr) return loadpkg(path.dirname(dir), cb);

lib/node-modules-paths.js

@@ -1,11 +1,14 @@
 var path = require('path');
 var parse = path.parse || require('path-parse'); // eslint-disable-line global-require
 
+var driveLetterRegex = /^([A-Za-z]:)/;
+var uncPathRegex = /^\\\\/;
+
 var getNodeModulesDirs = function getNodeModulesDirs(absoluteStart, modules) {
     var prefix = '/';
-    if ((/^([A-Za-z]:)/).test(absoluteStart)) {
+    if (driveLetterRegex.test(absoluteStart)) {
         prefix = '';
-    } else if ((/^\\\\/).test(absoluteStart)) {
+    } else if (uncPathRegex.test(absoluteStart)) {
         prefix = '\\\\';
     }
 

lib/sync.js

@@ -8,6 +8,10 @@ var normalizeOptions = require('./normalize-options');
 
 var realpathFS = process.platform !== 'win32' && fs.realpathSync && typeof fs.realpathSync.native === 'function' ? fs.realpathSync.native : fs.realpathSync;
 
+var relativePathRegex = /^(?:\.\.?(?:\/|$)|\/|([A-Za-z]:)?[/\\])/;
+var windowsDriveRegex = /^\w:[/\\]*$/;
+var nodeModulesRegex = /[/\\]node_modules[/\\]*$/;
+
 var homedir = getHomedir();
 var defaultPaths = function () {
     return [
@@ -96,7 +100,7 @@ module.exports = function resolveSync(x, options) {
     // ensure that `basedir` is an absolute path at this point, resolving against the process' current working directory
     var absoluteStart = maybeRealpathSync(realpathSync, path.resolve(basedir), opts);
 
-    if ((/^(?:\.\.?(?:\/|$)|\/|([A-Za-z]:)?[/\\])/).test(x)) {
+    if (relativePathRegex.test(x)) {
         var res = path.resolve(absoluteStart, x);
         if (x === '.' || x === '..' || x.slice(-1) === '/') res += '/';
         var m = loadAsFileSync(res) || loadAsDirectorySync(res);
@@ -137,10 +141,10 @@ module.exports = function resolveSync(x, options) {
 
     function loadpkg(dir) {
         if (dir === '' || dir === '/') return;
-        if (process.platform === 'win32' && (/^\w:[/\\]*$/).test(dir)) {
+        if (process.platform === 'win32' && windowsDriveRegex.test(dir)) {
             return;
         }
-        if ((/[/\\]node_modules[/\\]*$/).test(dir)) return;
+        if (nodeModulesRegex.test(dir)) return;
 
         var pkgfile = path.join(maybeRealpathSync(realpathSync, dir, opts), 'package.json');