wip

.changeset/stale-seals-impress.md

@@ -2,4 +2,4 @@
 '@segment/analytics-generic-utils': minor
 ---
 
-Add Emitter. Log warning if a specific event type exceeds 10
+Add Emitter library. Log default warning if a listeners exceeds 10 for a specific event type (configurable)

packages/generic-utils/src/emitter/__tests__/emitter.test.ts

@@ -74,13 +74,13 @@ describe(Emitter, () => {
 
   it('has a default max listeners of 10', () => {
     const em = new Emitter()
-    expect(em.maxListenersPerEvent).toBe(10)
+    expect(em.maxListeners).toBe(10)
   })
 
   it('should warn if possible memory leak', () => {
     const fn = jest.fn()
     const warnSpy = jest.spyOn(console, 'warn').mockImplementation(() => {})
-    const em = new Emitter({ maxListenersPerEvent: 3 })
+    const em = new Emitter({ maxListeners: 3 })
     em.on('test', fn)
     em.on('test', fn)
     em.on('test', fn)
@@ -96,8 +96,8 @@ describe(Emitter, () => {
   it('has no warning if maxListenersPerEvent is 0', () => {
     const fn = jest.fn()
     const warnSpy = jest.spyOn(console, 'warn').mockImplementation(() => {})
-    const em = new Emitter({ maxListenersPerEvent: 0 })
-    expect(em.maxListenersPerEvent).toBe(0)
+    const em = new Emitter({ maxListeners: 0 })
+    expect(em.maxListeners).toBe(0)
     em.on('test', fn)
     expect(warnSpy).not.toHaveBeenCalled()
     em.on('test', fn)

packages/generic-utils/src/emitter/emitter.ts

@@ -6,7 +6,7 @@ export interface EmitterOptions {
   /** How many event listeners for a particular event before emitting a warning (0 = disabled)
    *  @default 10
    **/
-  maxListenersPerEvent?: number
+  maxListeners?: number
 }
 
 /**
@@ -23,9 +23,9 @@ export interface EmitterOptions {
  * ```
  */
 export class Emitter<Contract extends EmitterContract = EmitterContract> {
-  maxListenersPerEvent: number
+  maxListeners: number
   constructor(options?: EmitterOptions) {
-    this.maxListenersPerEvent = options?.maxListenersPerEvent ?? 10
+    this.maxListeners = options?.maxListeners ?? 10
   }
   private callbacks: Partial<Contract> = {}
   private warned = false
@@ -37,13 +37,13 @@ export class Emitter<Contract extends EmitterContract = EmitterContract> {
       return
     }
     if (
-      this.maxListenersPerEvent &&
-      this.callbacks[event]!.length > this.maxListenersPerEvent
+      this.maxListeners &&
+      this.callbacks[event]!.length > this.maxListeners
     ) {
       console.warn(
         `Event Emitter: Possible memory leak detected; ${String(
           event
-        )} has exceeded ${this.maxListenersPerEvent} callbacks. `
+        )} has exceeded ${this.maxListeners} callbacks.`
       )
       this.warned = true
     }