BatchRequest assumes JSON RPC requests are returned in order

CHANGELOG.md

@@ -487,6 +487,7 @@ Released with 1.0.0-beta.37 code base.
 
 ### Fixed
  -  Fix readthedoc's build for web3js documentation (#4425)
+ -  Fix response sorting for batch requests (#4250)
 
 ### Changed
 

packages/web3-core-requestmanager/src/batch.js

@@ -47,8 +47,10 @@ Batch.prototype.add = function (request) {
  */
 Batch.prototype.execute = function () {
     var requests = this.requests;
+    var sortResponses = this._sortResponses.bind(this);
+
     this.requestManager.sendBatch(requests, function (err, results) {
-        results = results || [];
+        results = sortResponses(results);
         requests.map(function (request, index) {
             return results[index] || {};
         }).forEach(function (result, index) {
@@ -71,5 +73,10 @@ Batch.prototype.execute = function () {
     });
 };
 
+// Sort responses
+Batch.prototype._sortResponses = function (responses) {    
+    return (responses || []).sort((a, b) => a.id - b.id);
+}
+
 module.exports = Batch;
 

test/batch.js

@@ -6,6 +6,25 @@ var FakeIpcProvider = require('./helpers/FakeIpcProvider');
 
 
 describe('lib/web3/batch', function () {
+    describe('_sortResponses', function () {
+        it('should sort the responses in order of requests', function() {
+            var provider = new FakeIpcProvider();
+            var web3 = new Web3(provider);
+
+            var batch = new web3.BatchRequest();
+            batch.add(web3.eth.getBalance.request('0x0000000000000000000000000000000000000000', 'latest', () => {}));
+            batch.add(web3.eth.getBalance.request('0x0000000000000000000000000000000000000005', 'latest', () => {}));
+
+            const res1 = {id: 1, result: 'res1'}
+            const res2 = {id: 2, result: 'res2'}
+            const res3 = {id: 3, result: 'res3'}
+            const sortedResponses = batch._sortResponses([res3, res1, res2]);
+
+            assert.deepEqual(sortedResponses, [res1, res2, res3]);
+            batch.execute();
+        });
+    });
+
     describe('execute', function () {
         it('should execute batch request', function (done) {