Disable keep-alive on HTTP and HTTPS global agents on Node v19+.

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## Unreleased
 - Removes the [Underscore.js](https://underscorejs.org) dependency in favor of just inlining two rewritten helper functions.
+- Fixes possible double emitting on Node v19+ due to its global HTTP agent enabling keep-alive.
 
 ## 1.7.2 (May 1, 2021)
 - Increases the upper-bound on [Underscore.js](https://underscorejs.org) dependency to v1.13 (inclusive). 

index.js

@@ -13,6 +13,7 @@ var slice = Function.call.bind(Array.prototype.slice)
 var normalizeConnectArgs = Net._normalizeConnectArgs || Net._normalizeArgs
 var createRequestAndResponse = Http._connectionListener
 var NODE_0_10 = Semver.satisfies(process.version, ">= 0.10 < 0.11")
+var NODE_GTE_19 = Semver.satisfies(process.version, ">= 19")
 module.exports = Mitm
 
 function Mitm() {
@@ -61,6 +62,11 @@ Mitm.prototype.enable = function() {
  this.stubs.stub(Http.globalAgent, "maxSockets", Infinity)
  this.stubs.stub(Https.globalAgent, "maxSockets", Infinity)
  }
+ else if (NODE_GTE_19) {
+ // Note v19 enables keep-alive for both the Http and Https globalAgents.
+ this.stubs.stub(Http.globalAgent, "keepAlive", false)
+ this.stubs.stub(Https.globalAgent, "keepAlive", false)
+ }
 
  // ClientRequest.prototype.onSocket is called synchronously from
  // ClientRequest's constructor and is a convenient place to hook into new