feat: TS v4, tslint -> eslint, add cspell support (#240)

Update all dependencies, migrate from tslint (deprecated) to typescript-eslint, and add support for
cspell.

BREAKING CHANGE: migrated from tslint (deprecated) to eslint.

src/lib/async.spec.ts

@@ -1,7 +1,7 @@
-// tslint:disable:no-expression-statement
 import test from 'ava';
+
 import { asyncABC } from './async';
 
-test('getABC', async t => {
+test('getABC', async (t) => {
   t.deepEqual(await asyncABC(), ['a', 'b', 'c']);
 });

src/lib/async.ts

@@ -1,5 +1,5 @@
 /**
- * A sample async function (to demo Typescript's es7 async/await downleveling).
+ * A sample async function (to demo Typescript's es7 async/await down-leveling).
  *
  * ### Example (es imports)
  * ```js
@@ -15,18 +15,18 @@
  * // => ['a','b','c']
  * ```
  *
- * @returns       a Promise which should contain `['a','b','c']`
+ * @returns a Promise which should contain `['a','b','c']`
  */
-export async function asyncABC(): Promise<ReadonlyArray<string>> {
-  function somethingSlow(index: 0 | 1 | 2): Promise<string> {
+export const asyncABC = async () => {
+  const somethingSlow = (index: 0 | 1 | 2) => {
     const storage = 'abc'.charAt(index);
-    return new Promise<string>(resolve =>
+    return new Promise<string>((resolve) =>
       // later...
       resolve(storage)
     );
-  }
+  };
   const a = await somethingSlow(0);
   const b = await somethingSlow(1);
   const c = await somethingSlow(2);
   return [a, b, c];
-}
+};

src/lib/hash.spec.ts

@@ -1,11 +1,11 @@
-// tslint:disable:no-expression-statement no-object-mutation
 import test from 'ava';
+
 import { sha256, sha256Native } from './hash';
 
 test(
   'sha256',
-  (t, input: string, expected: string) => {
-    t.is(sha256(input), expected);
+  async (t, input: string, expected: string) => {
+    t.is(await sha256(input), expected);
     t.is(sha256Native(input), expected);
   },
   'test',

src/lib/hash.ts

@@ -1,5 +1,6 @@
 import { createHash } from 'crypto';
-import shaJs from 'sha.js';
+
+import { binToHex, instantiateSha256, utf8ToBin } from '@bitauth/libauth';
 
 /**
  * Calculate the sha256 digest of a string.
@@ -7,32 +8,34 @@ import shaJs from 'sha.js';
  * ### Example (es imports)
  * ```js
  * import { sha256 } from 'typescript-starter'
- * sha256('test')
- * // => '9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08'
+ *
+ * (async () => {
+ *   console.log(await sha256('test'));
+ *   // => '9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08'
+ * });
  * ```
  *
+ * @param message - the string to hash
  * @returns sha256 message digest
  */
-export function sha256(message: string): string {
-  return shaJs('sha256')
-    .update(message)
-    .digest('hex');
-}
+export const sha256 = async (message: string) => {
+  const sha256 = await instantiateSha256();
+  return binToHex(sha256.hash(utf8ToBin(message)));
+};
 
 /**
- * A faster implementation of [[sha256]] which requires the native Node.js module. Browser consumers should use [[sha256]], instead.
+ * A synchronous implementation of `sha256` which uses the native Node.js
+ * module. (Browser consumers should use the `sha256` method.)
  *
  * ### Example (es imports)
  * ```js
  * import { sha256Native as sha256 } from 'typescript-starter'
- * sha256('test')
+ * console.log(sha256('test'));
  * // => '9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08'
  * ```
- *
+ * @param message - the string to hash
  * @returns sha256 message digest
  */
-export function sha256Native(message: string): string {
-  return createHash('sha256')
-    .update(message)
-    .digest('hex');
-}
+export const sha256Native = (message: string) => {
+  return createHash('sha256').update(message).digest('hex');
+};

src/lib/number.spec.ts

@@ -1,11 +1,11 @@
-// tslint:disable:no-expression-statement
 import test from 'ava';
+
 import { double, power } from './number';
 
-test('double', t => {
+test('double', (t) => {
   t.is(double(2), 4);
 });
 
-test('power', t => {
+test('power', (t) => {
   t.is(power(2, 4), 16);
 });

src/lib/number.ts

@@ -1,5 +1,5 @@
 /**
- * Multiplies a value by 2. (Also a full example of Typedoc's functionality.)
+ * Multiplies a value by 2. (Also a full example of TypeDoc's functionality.)
  *
  * ### Example (es module)
  * ```js
@@ -15,16 +15,17 @@
  * // => 8
  * ```
  *
- * @param value   Comment describing the `value` parameter.
- * @returns       Comment describing the return type.
- * @anotherNote   Some other value.
+ * @param value - Comment describing the `value` parameter.
+ * @returns Comment describing the return type.
+ * @anotherNote Some other value.
  */
-export function double(value: number): number {
+export const double = (value: number) => {
   return value * 2;
-}
+};
 
 /**
- * Raise the value of the first parameter to the power of the second using the es7 `**` operator.
+ * Raise the value of the first parameter to the power of the second using the
+ * es7 exponentiation operator (`**`).
  *
  * ### Example (es module)
  * ```js
@@ -39,8 +40,12 @@ export function double(value: number): number {
  * console.log(power(2,3))
  * // => 8
  * ```
+ * @param base - the base to exponentiate
+ * @param exponent - the power to which to raise the base
  */
-export function power(base: number, exponent: number): number {
-  // This is a proposed es7 operator, which should be transpiled by Typescript
+export const power = (base: number, exponent: number) => {
+  /**
+   * This es7 exponentiation operator is transpiled by TypeScript
+   */
   return base ** exponent;
-}
+};