chore: include Engine.IO client v4

The ping-pong mechanism has been reverted (server now sends a ping and
expects a pong from the client), so we cannot compute the latency like
we did in previous versions.

Release notes: https://github.com/socketio/engine.io-client/releases/tag/4.0.0

build/manager.d.ts

@@ -15,7 +15,6 @@ export declare class Manager extends Emitter {
     private _reconnectionDelayMax;
     private _timeout;
     private connecting;
-    private lastPing;
     private encoding;
     private packetBuffer;
     private encoder;
@@ -118,12 +117,6 @@ export declare class Manager extends Emitter {
      * @api private
      */
     onping(): void;
-    /**
-     * Called upon a packet.
-     *
-     * @api private
-     */
-    onpong(): void;
     /**
      * Called with data.
      *

build/manager.js

@@ -49,7 +49,6 @@ class Manager extends component_emitter_1.default {
         this.nsps = {};
         this.subs = [];
         this.connecting = [];
-        this.lastPing = null;
         this.packetBuffer = [];
         if (uri && "object" === typeof uri) {
             opts = uri;
@@ -337,7 +336,6 @@ class Manager extends component_emitter_1.default {
         const socket = this.engine;
         this.subs.push(on_1.on(socket, "data", component_bind_1.default(this, "ondata")));
         this.subs.push(on_1.on(socket, "ping", component_bind_1.default(this, "onping")));
-        this.subs.push(on_1.on(socket, "pong", component_bind_1.default(this, "onpong")));
         this.subs.push(on_1.on(socket, "error", component_bind_1.default(this, "onerror")));
         this.subs.push(on_1.on(socket, "close", component_bind_1.default(this, "onclose")));
         this.subs.push(on_1.on(this.decoder, "decoded", component_bind_1.default(this, "ondecoded")));
@@ -348,17 +346,8 @@ class Manager extends component_emitter_1.default {
      * @api private
      */
     onping() {
-        this.lastPing = Date.now();
         this.emitAll("ping");
     }
-    /**
-     * Called upon a packet.
-     *
-     * @api private
-     */
-    onpong() {
-        this.emitAll("pong", Date.now() - this.lastPing);
-    }
     /**
      * Called with data.
      *
@@ -476,7 +465,6 @@ class Manager extends component_emitter_1.default {
         }
         this.packetBuffer = [];
         this.encoding = false;
-        this.lastPing = null;
         this.decoder.destroy();
     }
     /**

lib/manager.ts

@@ -34,7 +34,6 @@ export class Manager extends Emitter {
   private _timeout: any;
 
   private connecting: Array<Socket> = [];
-  private lastPing: number = null;
   private encoding: boolean;
   private packetBuffer: Array<any> = [];
   private encoder: Encoder;
@@ -363,7 +362,6 @@ export class Manager extends Emitter {
     const socket = this.engine;
     this.subs.push(on(socket, "data", bind(this, "ondata")));
     this.subs.push(on(socket, "ping", bind(this, "onping")));
-    this.subs.push(on(socket, "pong", bind(this, "onpong")));
     this.subs.push(on(socket, "error", bind(this, "onerror")));
     this.subs.push(on(socket, "close", bind(this, "onclose")));
     this.subs.push(on(this.decoder, "decoded", bind(this, "ondecoded")));
@@ -375,19 +373,9 @@ export class Manager extends Emitter {
    * @api private
    */
   onping() {
-    this.lastPing = Date.now();
     this.emitAll("ping");
   }
 
-  /**
-   * Called upon a packet.
-   *
-   * @api private
-   */
-  onpong() {
-    this.emitAll("pong", Date.now() - this.lastPing);
-  }
-
   /**
    * Called with data.
    *
@@ -515,7 +503,6 @@ export class Manager extends Emitter {
 
     this.packetBuffer = [];
     this.encoding = false;
-    this.lastPing = null;
 
     this.decoder.destroy();
   }

package.json

@@ -20,7 +20,7 @@
     "component-bind": "1.0.0",
     "component-emitter": "~1.3.0",
     "debug": "~3.1.0",
-    "engine.io-client": "~3.4.0",
+    "engine.io-client": "~4.0.0",
     "has-binary2": "~1.0.2",
     "indexof": "0.0.1",
     "parseqs": "0.0.6",

test/socket.js

@@ -47,22 +47,6 @@ describe("socket", function () {
     }, 300);
   });
 
-  it("should ping and pong with latency", (done) => {
-    const socket = io({ forceNew: true });
-    socket.on("connect", () => {
-      let pinged;
-      socket.once("ping", () => {
-        pinged = true;
-      });
-      socket.once("pong", (ms) => {
-        expect(pinged).to.be(true);
-        expect(ms).to.be.a("number");
-        socket.disconnect();
-        done();
-      });
-    });
-  });
-
   it("should change socket.id upon reconnection", (done) => {
     const socket = io({ forceNew: true });
     socket.on("connect", () => {