Update to version 1.1.0

Improved performance of the onceWhen method
Moved impl to global exports
Created EventLike interface for objects that look like EventEmitter but don't extend it
Improved testing sequence
Added build and test tasks
tslint now executes fix on build

.gitignore

@@ -61,4 +61,8 @@ typings/
 .next
 
 # ignore the distribution folder
-dist/
+dist/
+
+# vscode
+.vscode/*
+!.vscode/tasks.json

.vscode/tasks.json

@@ -0,0 +1,23 @@
+{
+    // See https://go.microsoft.com/fwlink/?LinkId=733558
+    // for the documentation about the tasks.json format
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "type": "npm",
+            "script": "build",
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            }
+        },
+        {
+            "type": "npm",
+            "script": "test",
+            "group": {
+                "kind": "test",
+                "isDefault": true
+            }
+        }
+    ]
+}

README.md

@@ -24,8 +24,17 @@ event.onceWhen('someEvent', (...) => /* predicate */, (...) => /* normal listene
 
 Method Name |   Description
 ----------- |   -----------
-<code>onWhen (event: string &#124; symbol, predicate: (...args: any[]) => boolean, listener (...args: any[]) => void): void</code>      |   Subscribe to the specified event, but only call the listener when the predicate is satisfied.
-<code>onceWhen (event: string &#124; symbol, predicate: (...args: any[]) => boolean, listener (...args: any[]) => void): void</code>    |   Subscribe to the specified event, calling the listener the first time the predicate is satisfied.
+<code>onWhen (event: string &#124; symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): this</code>      |   Subscribe to the specified event, but only call the listener when the predicate is satisfied.
+<code>onceWhen (event: string &#124; symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): this</code>    |   Subscribe to the specified event, calling the listener the first time the predicate is satisfied.
+
+`event-filter` also exports the following methods:
+
+Method Name |   Description
+----------- |   -----------
+<code>onWhen&lt;TEvent extends EventLike&gt; (evt: EventLike, event: string &#124; symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): TEvent</code> | Subscribe to the specified event, but only call the listener when the predicate is satisfied.
+<code>onceWhen&lt;TEvent extends EventLike&gt; (evt: EventLike, event: string &#124; symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): TEvent</code> | Subscribe to the specified event, calling the listener the first time the predicate is satisfied.
+
+Using these allows you to call `onWhen` and `onceWhen` on objects that are like `EventEmitter`, but don't actually extend the superclass.
 
 `event-filter` contains defines TypeScript definitions for type safety.
 

package.json

@@ -1,15 +1,16 @@
 {
   "name": "event-filter",
-  "version": "1.0.2",
+  "version": "1.1.0",
   "description": "A package for filtering Node.js events. Your listeners only get executed when the specified predicate is satisfied.",
   "main": "dist/index",
   "typing": "dist/index",
   "scripts": {
-    "test": "mocha -r ts-node/register src/**/*.spec.ts",
-    "lint": "tslint ./src/**.ts",
-    "prebuild": "npm run lint && rimraf ./dist",
-    "build": "tsc",
-    "watch:build": "tsc --watch"
+    "test": "npm run lint && npm run build && mocha -r ts-node/register src/**/*.spec.ts",
+    "lint:fix": "tslint --fix --config tslint.json --project src",
+    "lint": "tslint --config tslint.json --project src",
+    "prebuild": "npm run lint:fix && rimraf ./dist",
+    "build": "tsc --project src",
+    "watch:build": "tsc --watch --project src"
   },
   "author": "Olivia Trewin",
   "license": "MIT",

src/index.spec.ts

@@ -1,6 +1,7 @@
-import { EventEmitter } from 'events'
-import './index'
+import '.'
+
 import { expect } from 'chai'
+import { EventEmitter } from 'events'
 
 describe('onWhen', () => {
   it('should only fire when the condition is satisfied', () => {

src/index.ts

@@ -8,27 +8,46 @@ declare module 'events' {
      * @param {(...any) => boolean} predicate A function which validates the event data.
      * @param {(...any) => void} listener A listener to the event.
      */
-    onWhen (event: string | symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): void
+    onWhen (event: string | symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): this
 
     /**
      * Invoke a listener the first time a certain condition is satisfied.
      * @param {string | symbol} event The name of the event to listen to.
      * @param {(...any) => boolean} predicate A function which validates the event data.
      * @param {(...any) => void} listener A listener to the event.
      */
-    onceWhen (event: string | symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): void
+    onceWhen (event: string | symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): this
   }
 }
 
-EventEmitter.prototype.onWhen = function (this: EventEmitter, event, predicate, listener) {
-  this.on(event, (...args: any[]) => {
-    if (predicate(...args)) listener(...args)
-  })
+EventEmitter.prototype.onWhen = function <TArgs extends any[]> (this: EventEmitter, event: string | symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void) {
+  return onWhen(this, event, predicate, listener)
+}
+
+EventEmitter.prototype.onceWhen = function <TArgs extends any[]> (this: EventEmitter, event: string | symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void) {
+  return onceWhen(this, event, predicate, listener)
 }
 
-EventEmitter.prototype.onceWhen = function (this: EventEmitter, event, predicate, listener) {
-  this.once(event, (...args: any[]) => {
-    if (predicate(...args)) listener(...args)
-    else this.onceWhen(event, predicate, listener)
+interface EventLike {
+  on (event: string | symbol, listener: (...args: any[]) => void): this
+  removeListener (event: string | symbol, listener: (...args: any[]) => void): this
+}
+
+export function onWhen<TListener extends EventLike> (evt: TListener, event: string | symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): TListener {
+  return evt.on(event, (...args: any[]) => {
+    if (!predicate(...args)) return
+
+    listener(...args)
   })
 }
+
+export function onceWhen<TListener extends EventLike> (evt: TListener, event: string | symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): TListener {
+  return evt.on(event, onceHandler)
+
+  function onceHandler (...args: any[]) {
+    if (!predicate(...args)) return
+
+    listener(...args)
+    evt.removeListener(event, onceHandler)
+  }
+}

src/tsconfig.json

@@ -0,0 +1,65 @@
+{
+  "compilerOptions": {
+    /* Basic Options */
+    "target": "es5",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */
+    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
+    "lib": [
+        "es5",
+        "es6"
+    ],                             /* Specify library files to be included in the compilation. */
+    // "allowJs": true,                       /* Allow javascript files to be compiled. */
+    // "checkJs": true,                       /* Report errors in .js files. */
+    // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
+    "declaration": true,                   /* Generates corresponding '.d.ts' file. */
+    // "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. */
+    // "sourceMap": true,                     /* Generates corresponding '.map' file. */
+    // "outFile": "./",                       /* Concatenate and emit output to single file. */
+    "outDir": "../dist",                        /* Redirect output structure to the directory. */
+    // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
+    // "composite": true,                     /* Enable project compilation */
+    // "removeComments": true,                /* Do not emit comments to output. */
+    // "noEmit": true,                        /* Do not emit outputs. */
+    // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
+    // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
+    // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
+
+    /* Strict Type-Checking Options */
+    "strict": true,                           /* Enable all strict type-checking options. */
+    "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
+    "strictNullChecks": true,              /* Enable strict null checks. */
+    "strictFunctionTypes": true,           /* Enable strict checking of function types. */
+    "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
+    "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
+    // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
+
+    /* Additional Checks */
+    // "noUnusedLocals": true,                /* Report errors on unused locals. */
+    // "noUnusedParameters": true,            /* Report errors on unused parameters. */
+    // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
+    // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
+
+    /* Module Resolution Options */
+    "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
+    // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
+    // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
+    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
+    // "typeRoots": [],                       /* List of folders to include type definitions from. */
+    // "types": [],                           /* Type declaration files to be included in compilation. */
+    // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
+    "esModuleInterop": true,                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
+    // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+
+    /* Source Map Options */
+    // "sourceRoot": "./",                    /* Specify the location where debugger should locate TypeScript files instead of source locations. */
+    // "mapRoot": "./",                       /* Specify the location where debugger should locate map files instead of generated locations. */
+    "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
+    "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
+
+    /* Experimental Options */
+    // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
+    // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
+  },
+  "exclude": [
+      "*.spec.ts"
+  ]
+}