Require Node.js 12 and move to ESM

Closes #132
Closes #127

.github/workflows/main.yml

@@ -12,7 +12,6 @@ jobs:
         node-version:
           - 14
           - 12
-          - 10
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v1

bench.ts

@@ -1,6 +1,5 @@
-import Benchmark = require('benchmark');
-import {Deferred, Event} from 'benchmark';
-import PQueue from './source';
+import Benchmark, {Deferred, Event} from 'benchmark';
+import PQueue from './source/index.js';
 
 const suite = new Benchmark.Suite();
 
@@ -54,7 +53,6 @@ suite
 			}
 
 			await queue.onEmpty();
-			// @ts-expect-error benchmark typings incorrect
 			deferred.resolve();
 		}
 	})

package.json

@@ -5,14 +5,15 @@
 	"license": "MIT",
 	"repository": "sindresorhus/p-queue",
 	"funding": "https://github.com/sponsors/sindresorhus",
-	"main": "dist/index.js",
+	"type": "module",
+	"exports": "./dist/index.js",
 	"engines": {
-		"node": ">=10"
+		"node": ">=12"
 	},
 	"scripts": {
 		"build": "del dist && tsc",
 		"test": "xo && npm run build && nyc ava",
-		"bench": "ts-node bench.ts",
+		"bench": "node --loader=ts-node/esm bench.ts",
 		"prepublishOnly": "npm run build"
 	},
 	"files": [
@@ -46,41 +47,40 @@
 		"p-timeout": "^4.1.0"
 	},
 	"devDependencies": {
-		"@sindresorhus/tsconfig": "^0.7.0",
+		"@sindresorhus/tsconfig": "^1.0.0",
 		"@types/benchmark": "^2.1.0",
-		"@types/node": "^14.14.19",
-		"ava": "^2.4.0",
+		"@types/node": "^14.14.37",
+		"ava": "^3.15.0",
 		"benchmark": "^2.1.4",
 		"codecov": "^3.8.1",
 		"del-cli": "^3.0.1",
-		"delay": "^4.4.0",
-		"in-range": "^2.0.0",
+		"delay": "^5.0.0",
+		"in-range": "^3.0.0",
 		"nyc": "^15.1.0",
 		"random-int": "^2.0.1",
 		"time-span": "^4.0.0",
 		"ts-node": "^9.1.1",
-		"typescript": "^4.1.3",
-		"xo": "^0.37.1"
+		"typescript": "^4.2.3",
+		"xo": "^0.38.2"
 	},
 	"ava": {
-		"babel": false,
-		"compileEnhancements": false,
-		"extensions": [
-			"ts"
-		],
-		"require": [
-			"ts-node/register"
-		],
 		"files": [
 			"test/**"
+		],
+		"extensions": {
+			"ts": "module"
+		},
+		"nonSemVerExperiments": {
+			"configurableModuleFormat": true
+		},
+		"nodeArguments": [
+			"--loader=ts-node/esm"
 		]
 	},
 	"xo": {
 		"rules": {
 			"@typescript-eslint/member-ordering": "off",
-			"node/no-unsupported-features/es-syntax": "off",
 			"@typescript-eslint/no-floating-promises": "off",
-			"import/no-named-default": "off",
 			"@typescript-eslint/no-invalid-void-type": "off"
 		}
 	},

readme.md

@@ -15,8 +15,8 @@ $ npm install p-queue
 Here we run only one promise at the time. For example, set `concurrency` to 4 to run four promises at the same time.
 
 ```js
-const {default: PQueue} = require('p-queue');
-const got = require('got');
+import PQueue from 'p-queue';
+import got from 'got';
 
 const queue = new PQueue({concurrency: 1});
 
@@ -170,6 +170,8 @@ Size of the queue, filtered by the given options.
 For example, this can be used to find the number of items remaining in the queue with a specific priority level.
 
 ```js
+import PQueue from 'p-queue';
+
 const queue = new PQueue();
 
 queue.add(async () => '🦄', {priority: 1});
@@ -202,8 +204,8 @@ Whether the queue is currently paused.
 Emitted as each item is processed in the queue for the purpose of tracking progress.
 
 ```js
-const delay = require('delay');
-const {default: PQueue} = require('p-queue');
+import delay from 'delay';
+import PQueue from 'p-queue';
 
 const queue = new PQueue({concurrency: 2});
 
@@ -218,13 +220,14 @@ queue.add(() => Promise.resolve());
 queue.add(() => Promise.resolve());
 queue.add(() => delay(500));
 ```
+
 #### idle
 
 Emitted every time the queue becomes empty and all promises have completed; `queue.size === 0 && queue.pending === 0`.
 
 ```js
-const delay = require('delay');
-const {default: PQueue} = require('p-queue');
+import delay from 'delay';
+import PQueue from 'p-queue';
 
 const queue = new PQueue();
 
@@ -254,14 +257,15 @@ Emitted every time the add method is called and the number of pending or queued
 Emitted every time a task is completed and the number of pending or queued tasks is decreased.
 
 ```js
-const delay = require('delay');
-const {default: PQueue} = require('p-queue');
+import delay from 'delay';
+import PQueue from 'p-queue';
 
 const queue = new PQueue();
 
 queue.on('add', () => {
 	console.log(`Task is added.  Size: ${queue.size}  Pending: ${queue.pending}`);
 });
+
 queue.on('next', () => {
 	console.log(`Task is completed.  Size: ${queue.size}  Pending: ${queue.pending}`);
 });
@@ -284,8 +288,8 @@ await queue.add(() => delay(600));
 A more advanced example to help you understand the flow.
 
 ```js
-const delay = require('delay');
-const {default: PQueue} = require('p-queue');
+import delay from 'delay';
+import PQueue from 'p-queue';
 
 const queue = new PQueue({concurrency: 1});
 
@@ -354,6 +358,8 @@ $ node example.js
 For implementing more complex scheduling policies, you can provide a QueueClass in the options:
 
 ```js
+import PQueue from 'p-queue';
+
 class QueueClass {
 	constructor() {
 		this._queue = [];
@@ -376,9 +382,7 @@ class QueueClass {
 	}
 }
 
-const queue = new PQueue({
-	queueClass: QueueClass
-});
+const queue = new PQueue({queueClass: QueueClass});
 ```
 
 `p-queue` will call corresponding methods to put and get operations from this queue.

source/index.ts

@@ -1,8 +1,8 @@
-import EventEmitter = require('eventemitter3');
-import {default as pTimeout, TimeoutError} from 'p-timeout';
-import {Queue, RunFunction} from './queue';
-import PriorityQueue from './priority-queue';
-import {QueueAddOptions, DefaultAddOptions, Options} from './options';
+import EventEmitter from 'eventemitter3';
+import pTimeout, {TimeoutError} from 'p-timeout';
+import {Queue, RunFunction} from './queue.js';
+import PriorityQueue from './priority-queue.js';
+import {QueueAddOptions, DefaultAddOptions, Options} from './options.js';
 
 type ResolveFunction<T = void> = (value?: T | PromiseLike<T>) => void;
 

source/lower-bound.ts

@@ -8,7 +8,7 @@ export default function lowerBound<T>(array: readonly T[], value: T, comparator:
 		const step = Math.trunc(count / 2);
 		let it = first + step;
 
-		if (comparator(array[it], value) <= 0) {
+		if (comparator(array[it]!, value) <= 0) {
 			first = ++it;
 			count -= step + 1;
 		} else {

source/options.ts

@@ -1,4 +1,4 @@
-import {Queue, RunFunction} from './queue';
+import {Queue, RunFunction} from './queue.js';
 
 export type QueueAddOptions = Readonly<Record<string, unknown>>;
 

source/priority-queue.ts

@@ -1,6 +1,6 @@
-import {Queue, RunFunction} from './queue';
-import lowerBound from './lower-bound';
-import {QueueAddOptions} from './options';
+import {Queue, RunFunction} from './queue.js';
+import lowerBound from './lower-bound.js';
+import {QueueAddOptions} from './options.js';
 
 export interface PriorityQueueOptions extends QueueAddOptions {
 	priority?: number;
@@ -20,7 +20,7 @@ export default class PriorityQueue implements Queue<RunFunction, PriorityQueueOp
 			run
 		};
 
-		if (this.size && this._queue[this.size - 1].priority! >= options.priority!) {
+		if (this.size && this._queue[this.size - 1]?.priority! >= options.priority!) {
 			this._queue.push(element);
 			return;
 		}
@@ -40,7 +40,7 @@ export default class PriorityQueue implements Queue<RunFunction, PriorityQueueOp
 	filter(options: Readonly<Partial<PriorityQueueOptions>>): RunFunction[] {
 		return this._queue.filter(
 			(element: Readonly<PriorityQueueOptions>) => element.priority === options.priority
-		).map((element: Readonly<{ run: RunFunction }>) => element.run);
+		).map((element: Readonly<{run: RunFunction}>) => element.run);
 	}
 
 	get size(): number {