Disable client Helpers in Node.js < 10.

.github/workflows/nodejs.yml

@@ -63,7 +63,7 @@ jobs:
 
     - name: Test
       run: |
-        npm run test:unit -- --node-arg=--harmony-async-iteration
+        npm run test:node8
 
   helpers-integration-test:
     name: Helpers integration test

docs/helpers.asciidoc

@@ -4,8 +4,7 @@
 The client comes with an handy collection of helpers to give you a more comfortable experience with some APIs.
 
 CAUTION: The client helpers are experimental, and the API may change in the next minor releases.
-If you are using the client with Node.js v8 you should run your code with the `--harmony-async-iteration` argument. +
-eg: `node --harmony-async-iteration index.js`
+The helpers will not work in any Node.js version lower than 10.
 
 === Bulk Helper
 Running Bulk requests can be complex due to the shape of the API, this helper aims to provide a nicer developer experience around the Bulk API.

index.js

@@ -4,13 +4,16 @@
 
 'use strict'
 
+const nodeMajor = Number(process.versions.node.split('.')[0])
+
 const { EventEmitter } = require('events')
 const { URL } = require('url')
 const debug = require('debug')('elasticsearch')
 const Transport = require('./lib/Transport')
 const Connection = require('./lib/Connection')
 const { ConnectionPool, CloudConnectionPool } = require('./lib/pool')
-const Helpers = require('./lib/Helpers')
+// Helpers works only in Node.js >= 10
+const Helpers = nodeMajor < 10 ? null : require('./lib/Helpers')
 const Serializer = require('./lib/Serializer')
 const errors = require('./lib/errors')
 const { ConfigurationError } = errors
@@ -127,7 +130,9 @@ class Client extends EventEmitter {
       opaqueIdPrefix: options.opaqueIdPrefix
     })
 
-    this.helpers = new Helpers({ client: this, maxRetries: options.maxRetries })
+    if (Helpers !== null) {
+      this.helpers = new Helpers({ client: this, maxRetries: options.maxRetries })
+    }
 
     const apis = buildApi({
       makeRequest: this.transport.request.bind(this.transport),

package.json

@@ -17,6 +17,7 @@
   ],
   "scripts": {
     "test": "npm run lint && npm run test:unit && npm run test:behavior && npm run test:types",
+    "test:node8": "npm run lint && tap test/unit/*.test.js -t 300 --no-coverage && npm run test:behavior && npm run test:types",
     "test:unit": "tap test/unit/*.test.js test/unit/**/*.test.js -t 300 --no-coverage",
     "test:behavior": "tap test/behavior/*.test.js -t 300 --no-coverage",
     "test:integration": "node test/integration/index.js",