adapter: simplify compareByIdThenRev() (#8787)

Author: alxndrsn

packages/node_modules/pouchdb-core/src/adapter.js

@@ -40,10 +40,6 @@ import {
  * A generic pouch adapter
  */
 
-function compare(left, right) {
-  return left < right ? -1 : left > right ? 1 : 0;
-}
-
 // Wrapper for functions that call the bulkdocs api with a single doc,
 // if the first result is an error, return an error
 function yankError(callback, docId) {
@@ -78,13 +74,12 @@ function cleanDocs(docs) {
 
 // compare two docs, first by _id then by _rev
 function compareByIdThenRev(a, b) {
-  var idCompare = compare(a._id, b._id);
-  if (idCompare !== 0) {
-    return idCompare;
+  if (a._id === b._id) {
+    const aStart = a._revisions ? a._revisions.start : 0;
+    const bStart = b._revisions ? b._revisions.start : 0;
+    return aStart - bStart;
   }
-  var aStart = a._revisions ? a._revisions.start : 0;
-  var bStart = b._revisions ? b._revisions.start : 0;
-  return compare(aStart, bStart);
+  return a._id < b._id ? -1 : 1;
 }
 
 // for every node in a revision tree computes its distance from the closest