path: refactor code for clarity

This moves a condition inside of a for loop which can only be
triggered at the very end of the for loop outside of the loop. That
way the for loop itself is much simpler and easier to understand and
the code itself is less indented which should increase the
readability.

It also refactors some `var` to `let` and `const`.

PR-URL: https://github.com/nodejs/node/pull/25278
Reviewed-By: Michaël Zasso <targos@protonmail.com>

1 files changed, 63 insertions, 65 deletions

diff --git a/lib/path.js b/lib/path.js
index 64cd5eee92c..6ac65cfe4a7 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -478,38 +478,12 @@ const win32 = {
     const toLen = toEnd - toStart;
 
     // Compare paths to find the longest common path from root
-    var length = (fromLen < toLen ? fromLen : toLen);
-    var lastCommonSep = -1;
-    var i = 0;
-    for (; i <= length; ++i) {
-      if (i === length) {
-        if (toLen > length) {
-          if (to.charCodeAt(toStart + i) === CHAR_BACKWARD_SLASH) {
-            // We get here if `from` is the exact base path for `to`.
-            // For example: from='C:\\foo\\bar'; to='C:\\foo\\bar\\baz'
-            return toOrig.slice(toStart + i + 1);
-          } else if (i === 2) {
-            // We get here if `from` is the device root.
-            // For example: from='C:\\'; to='C:\\foo'
-            return toOrig.slice(toStart + i);
-          }
-        }
-        if (fromLen > length) {
-          if (from.charCodeAt(fromStart + i) === CHAR_BACKWARD_SLASH) {
-            // We get here if `to` is the exact base path for `from`.
-            // For example: from='C:\\foo\\bar'; to='C:\\foo'
-            lastCommonSep = i;
-          } else if (i === 2) {
-            // We get here if `to` is the device root.
-            // For example: from='C:\\foo\\bar'; to='C:\\'
-            lastCommonSep = 3;
-          }
-        }
-        break;
-      }
-      var fromCode = from.charCodeAt(fromStart + i);
-      var toCode = to.charCodeAt(toStart + i);
-      if (fromCode !== toCode)
+    const length = fromLen < toLen ? fromLen : toLen;
+    let lastCommonSep = -1;
+    let i = 0;
+    for (; i < length; i++) {
+      const fromCode = from.charCodeAt(fromStart + i);
+      if (fromCode !== to.charCodeAt(toStart + i))
         break;
       else if (fromCode === CHAR_BACKWARD_SLASH)
         lastCommonSep = i;
@@ -517,8 +491,33 @@ const win32 = {
 
     // We found a mismatch before the first common path separator was seen, so
     // return the original `to`.
-    if (i !== length && lastCommonSep === -1) {
-      return toOrig;
+    if (i !== length) {
+      if (lastCommonSep === -1)
+        return toOrig;
+    } else {
+      if (toLen > length) {
+        if (to.charCodeAt(toStart + i) === CHAR_BACKWARD_SLASH) {
+          // We get here if `from` is the exact base path for `to`.
+          // For example: from='C:\\foo\\bar'; to='C:\\foo\\bar\\baz'
+          return toOrig.slice(toStart + i + 1);
+        }
+        if (i === 2) {
+          // We get here if `from` is the device root.
+          // For example: from='C:\\'; to='C:\\foo'
+          return toOrig.slice(toStart + i);
+        }
+      }
+      if (fromLen > length) {
+        if (from.charCodeAt(fromStart + i) === CHAR_BACKWARD_SLASH) {
+          // We get here if `to` is the exact base path for `from`.
+          // For example: from='C:\\foo\\bar'; to='C:\\foo'
+          lastCommonSep = i;
+        } else if (i === 2) {
+          // We get here if `to` is the device root.
+          // For example: from='C:\\foo\\bar'; to='C:\\'
+          lastCommonSep = 3;
+        }
+      }
     }
 
     let out = '';
@@ -1079,41 +1078,40 @@ const posix = {
     const toLen = (toEnd - toStart);
 
     // Compare paths to find the longest common path from root
-    var length = (fromLen < toLen ? fromLen : toLen);
-    var lastCommonSep = -1;
-    var i = 0;
-    for (; i <= length; ++i) {
-      if (i === length) {
-        if (toLen > length) {
-          if (to.charCodeAt(toStart + i) === CHAR_FORWARD_SLASH) {
-            // We get here if `from` is the exact base path for `to`.
-            // For example: from='/foo/bar'; to='/foo/bar/baz'
-            return to.slice(toStart + i + 1);
-          } else if (i === 0) {
-            // We get here if `from` is the root
-            // For example: from='/'; to='/foo'
-            return to.slice(toStart + i);
-          }
-        } else if (fromLen > length) {
-          if (from.charCodeAt(fromStart + i) === CHAR_FORWARD_SLASH) {
-            // We get here if `to` is the exact base path for `from`.
-            // For example: from='/foo/bar/baz'; to='/foo/bar'
-            lastCommonSep = i;
-          } else if (i === 0) {
-            // We get here if `to` is the root.
-            // For example: from='/foo'; to='/'
-            lastCommonSep = 0;
-          }
-        }
-        break;
-      }
-      var fromCode = from.charCodeAt(fromStart + i);
-      var toCode = to.charCodeAt(toStart + i);
-      if (fromCode !== toCode)
+    const length = (fromLen < toLen ? fromLen : toLen);
+    let lastCommonSep = -1;
+    let i = 0;
+    for (; i < length; i++) {
+      const fromCode = from.charCodeAt(fromStart + i);
+      if (fromCode !== to.charCodeAt(toStart + i))
         break;
       else if (fromCode === CHAR_FORWARD_SLASH)
         lastCommonSep = i;
     }
+    if (i === length) {
+      if (toLen > length) {
+        if (to.charCodeAt(toStart + i) === CHAR_FORWARD_SLASH) {
+          // We get here if `from` is the exact base path for `to`.
+          // For example: from='/foo/bar'; to='/foo/bar/baz'
+          return to.slice(toStart + i + 1);
+        }
+        if (i === 0) {
+          // We get here if `from` is the root
+          // For example: from='/'; to='/foo'
+          return to.slice(toStart + i);
+        }
+      } else if (fromLen > length) {
+        if (from.charCodeAt(fromStart + i) === CHAR_FORWARD_SLASH) {
+          // We get here if `to` is the exact base path for `from`.
+          // For example: from='/foo/bar/baz'; to='/foo/bar'
+          lastCommonSep = i;
+        } else if (i === 0) {
+          // We get here if `to` is the root.
+          // For example: from='/foo'; to='/'
+          lastCommonSep = 0;
+        }
+      }
+    }
 
     var out = '';
     // Generate the relative path based on the path difference between `to`