Require Node.js 8

.travis.yml

@@ -2,4 +2,3 @@ language: node_js
 node_js:
   - '10'
   - '8'
-  - '6'

package.json

@@ -11,7 +11,7 @@
 	},
 	"main": "dist",
 	"engines": {
-		"node": ">=6"
+		"node": ">=8"
 	},
 	"scripts": {
 		"build": "del dist && tsc",
@@ -54,11 +54,13 @@
 		"@typescript-eslint/eslint-plugin": "^1.5.0",
 		"ava": "^1.4.1",
 		"del-cli": "^1.1.0",
+		"eslint-config-xo-typescript": "^0.9.0",
 		"jsdom": "^11.6.2",
 		"rxjs": "^6.4.0",
 		"tempy": "^0.2.1",
 		"ts-node": "^8.0.3",
 		"typescript": "^3.4.1",
+		"xo": "^0.24.0",
 		"zen-observable": "^0.8.8"
 	},
 	"types": "dist",

source/index.ts

@@ -1,5 +1,4 @@
-/// <reference lib="es2016"/>
+/// <reference lib="es2017"/>
-/// <reference lib="es2017.sharedmemory"/>
 /// <reference lib="esnext.asynciterable"/>
 /// <reference lib="dom"/>
 
@@ -145,7 +144,7 @@ is.nativePromise = (value: unknown): value is Promise<unknown> =>
 const hasPromiseAPI = (value: unknown): value is Promise<unknown> =>
 	!is.null_(value) &&
 	isObject(value) as unknown &&
-	is.function_((value as Promise<unknown>).then) &&
+	is.function_((value as Promise<unknown>).then) && // eslint-disable-line promise/prefer-await-to-then
 	is.function_((value as Promise<unknown>).catch);
 
 is.promise = (value: unknown): value is Promise<unknown> => is.nativePromise(value) || hasPromiseAPI(value);
@@ -180,7 +179,7 @@ is.arrayBuffer = isObjectOfType<ArrayBuffer>(TypeName.ArrayBuffer);
 is.sharedArrayBuffer = isObjectOfType<SharedArrayBuffer>(TypeName.SharedArrayBuffer);
 is.dataView = isObjectOfType<DataView>(TypeName.DataView);
 
-is.directInstanceOf = <T>(instance: unknown, klass: Class<T>): instance is T => Object.getPrototypeOf(instance) === klass.prototype;
+is.directInstanceOf = <T>(instance: unknown, class_: Class<T>): instance is T => Object.getPrototypeOf(instance) === class_.prototype;
 is.urlInstance = (value: unknown): value is URL => isObjectOfType<URL>(TypeName.URL)(value);
 
 is.urlString = (value: unknown): value is string => {

test/test.ts

@@ -10,7 +10,6 @@ import {Subject, Observable} from 'rxjs';
 import ZenObservable from 'zen-observable';
 import is from '../source';
 
-const isNode8orHigher = Number(process.versions.node.split('.')[0]) >= 8;
 const isNode10orHigher = Number(process.versions.node.split('.')[0]) >= 10;
 
 class PromiseSubclassFixture<T> extends Promise<T> {}
@@ -223,55 +222,55 @@ const types = new Map<string, Test>([
 	['int8Array', {
 		is: is.int8Array,
 		fixtures: [
-			new Int8Array(0)
+			new Int8Array()
 		]
 	}],
 	['uint8Array', {
 		is: is.uint8Array,
 		fixtures: [
-			new Uint8Array(0)
+			new Uint8Array()
 		]
 	}],
 	['uint8ClampedArray', {
 		is: is.uint8ClampedArray,
 		fixtures: [
-			new Uint8ClampedArray(0)
+			new Uint8ClampedArray()
 		]
 	}],
 	['int16Array', {
 		is: is.int16Array,
 		fixtures: [
-			new Int16Array(0)
+			new Int16Array()
 		]
 	}],
 	['uint16Array', {
 		is: is.uint16Array,
 		fixtures: [
-			new Uint16Array(0)
+			new Uint16Array()
 		]
 	}],
 	['int32Array', {
 		is: is.int32Array,
 		fixtures: [
-			new Int32Array(0)
+			new Int32Array()
 		]
 	}],
 	['uint32Array', {
 		is: is.uint32Array,
 		fixtures: [
-			new Uint32Array(0)
+			new Uint32Array()
 		]
 	}],
 	['float32Array', {
 		is: is.float32Array,
 		fixtures: [
-			new Float32Array(0)
+			new Float32Array()
 		]
 	}],
 	['float64Array', {
 		is: is.float64Array,
 		fixtures: [
-			new Float64Array(0)
+			new Float64Array()
 		]
 	}],
 	['arrayBuffer', {
@@ -480,21 +479,17 @@ test('is.error', t => {
 	testType(t, 'error');
 });
 
-if (isNode8orHigher) {
+test('is.nativePromise', t => {
-	test('is.nativePromise', t => {
+	testType(t, 'nativePromise');
-		testType(t, 'nativePromise');
+});
-	});
 
-	test('is.promise', t => {
+test('is.promise', t => {
-		testType(t, 'promise', ['nativePromise']);
+	testType(t, 'promise', ['nativePromise']);
-	});
+});
 
-	/*-
+test('is.asyncFunction', t => {
-	test('is.asyncFunction', t => {
+	testType(t, 'asyncFunction', ['function']);
-		testType(t, 'asyncFunction', ['function']);
+});
-	});
-	*/
-}
 
 test('is.generator', t => {
 	testType(t, 'generator');
@@ -691,18 +686,15 @@ test('is.class', t => {
 });
 
 test('is.typedArray', t => {
-	// TypeScript currently does not support empty constructors for these
-	// See https://github.com/Microsoft/TypeScript/issues/19680
-	// TODO: Remove the `0` when targeting `es2017` (Node.js 8), in other places of this file too.
 	const typedArrays = [
-		new Int8Array(0),
+		new Int8Array(),
-		new Uint8Array(0),
+		new Uint8Array(),
-		new Uint8ClampedArray(0),
+		new Uint8ClampedArray(),
-		new Uint16Array(0),
+		new Uint16Array(),
-		new Int32Array(0),
+		new Int32Array(),
-		new Uint32Array(0),
+		new Uint32Array(),
-		new Float32Array(0),
+		new Float32Array(),
-		new Float64Array(0)
+		new Float64Array()
 	];
 
 	for (const item of typedArrays) {

tsconfig.json

@@ -2,10 +2,9 @@
 	"extends": "@sindresorhus/tsconfig",
 	"compilerOptions": {
 		"outDir": "dist",
-		"target": "es2016",
+		"target": "es2017",
 		"lib": [
-			"es2016",
+			"es2017",
-			"es2017.sharedmemory",
 			"esnext.asynciterable",
 			"dom"
 		]