test and support older versions of node

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
     container: "node:${{matrix.node}}"
     strategy:
       matrix:
-        node: ["16"]
+        node: ["12", "14", "16"]
     services:
       redis-single-instance:
         image: redis

package.json

@@ -56,7 +56,9 @@
     "prepare": "yarn build",
     "prepublishOnly": "yarn install && yarn lint && yarn build && yarn test"
   },
-  "dependencies": {},
+  "dependencies": {
+    "node-abort-controller": "^2.0.0"
+  },
   "type": "module",
   "exports": "./dist/index.js"
 }

src/index.ts

@@ -1,6 +1,10 @@
 import { randomBytes, createHash } from "crypto";
 import { EventEmitter } from "events";
 
+// AbortController became available as a global in node version 16. Once version
+// 14 reaches its end-of-life, this can be removed.
+import PolyfillAbortController from "node-abort-controller";
+
 import { Redis as IORedisClient } from "ioredis";
 type Client = IORedisClient;
 
@@ -679,7 +683,11 @@ export default class Redlock extends EventEmitter {
     // The AbortController/AbortSignal pattern allows the routine to be notified
     // of a failure to extend the lock, and subsequent expiration. In the event
     // of an abort, the error object will be made available at `signal.error`.
-    const controller = new AbortController();
+    const controller =
+      typeof AbortController === "undefined"
+        ? new PolyfillAbortController()
+        : new AbortController();
+
     const signal = controller.signal as RedlockAbortSignal;
 
     function queue(): void {

tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "lib": ["es2020"],
-    "target": "es2020",
+    "target": "es2018",
     "module": "es2020",
     "outDir": "./dist",
     "declaration": true,