feat: drop Node.js v12 support

BREAKING CHANGE: Node.js v12 is no longer supported.

.eslintrc

@@ -1,6 +1,3 @@
 {
-  "extends": "@kenan",
-  "rules": {
-    "no-var": 0
-  }
+  "extends": "@kenan"
 }

.github/renovate.json

@@ -1,3 +1,6 @@
 {
-  "extends": ["local>kenany/renovate-config"]
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": ["local>kenany/renovate-config"],
+  "assignees": ["kenany"],
+  "reviewers": ["kenany"]
 }

.github/workflows/nodejs.yml

@@ -5,7 +5,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        node-version: [12, 14, 16, 18]
+        node-version: [14, 16, 18]
         os: [ubuntu-latest]
     steps:
     - uses: actions/checkout@v3.0.2

.github/workflows/release.yml

@@ -10,7 +10,7 @@ jobs:
     steps:
       - uses: actions/setup-node@v3.5.0
         with:
-          node-version: 16
+          node-version: 18
       - name: Update npm
         run: |
           npm install -g npm

README.md

@@ -18,14 +18,14 @@ player play a match against each of the other 999 players. After each individual
 match, I calculate the new ratings of the first player and his opponent. The
 result:
 
-``` sh
+``` bash
 $ node bench/index.js
 
 Starting...
   2 tests completed.
 
-  glicko2-lite x   433 ops/sec ±0.42% (87 runs sampled)
-  glicko2      x 33.84 ops/sec ±1.40% (59 runs sampled)
+  glicko2-lite x   677 ops/sec ±0.48% (89 runs sampled)
+  glicko2      x 33.62 ops/sec ±1.19% (59 runs sampled)
 ```
 
    [1]: https://github.com/mmai/glicko2js

index.js

@@ -1,9 +1,5 @@
 'use strict';
 
-var assign = require('lodash.assign');
-var map = require('lodash.map');
-var reduce = require('lodash.reduce');
-
 /** @typedef {[rating: number, rd: number, vol: number]} Opponent */
 
 /**
@@ -21,9 +17,9 @@ var reduce = require('lodash.reduce');
  * @param {{ rating: number; }} options
  */
 function scale(rating, rd, options) {
-  var mu = (rating - options.rating) / 173.7178;
-  var phi = rd / 173.7178;
-  return { mu: mu, phi: phi };
+  const mu = (rating - options.rating) / 173.7178;
+  const phi = rd / 173.7178;
+  return { mu, phi };
 }
 
 /**
@@ -51,8 +47,8 @@ function e(mu, muj, phij) {
  * @returns {ScaledOpponent[]}
  */
 function scaleOpponents(mu, opponents, options) {
-  return map(opponents, function(opp) {
-    var scaled = scale(opp[0], opp[1], options);
+  return opponents.map((opp) => {
+    const scaled = scale(opp[0], opp[1], options);
     return {
       muj: scaled.mu,
       phij: scaled.phi,
@@ -68,9 +64,10 @@ function scaleOpponents(mu, opponents, options) {
  * @returns {number}
  */
 function updateRating(opponents) {
-  return 1 / reduce(opponents, function(sum, opp) {
-    return sum + Math.pow(opp.gphij, 2) * opp.emmp * (1 - opp.emmp);
-  }, 0);
+  return 1 / opponents.reduce(
+    (sum, opp) => sum + Math.pow(opp.gphij, 2) * opp.emmp * (1 - opp.emmp),
+    0
+  );
 }
 
 /**
@@ -79,9 +76,10 @@ function updateRating(opponents) {
  * @returns {number}
  */
 function computeDelta(v, opponents) {
-  return v * reduce(opponents, function(sum, opp) {
-    return sum + opp.gphij * (opp.score - opp.emmp);
-  }, 0);
+  return v * opponents.reduce(
+    (sum, opp) => sum + opp.gphij * (opp.score - opp.emmp),
+    0
+  );
 }
 
 /**
@@ -92,17 +90,17 @@ function computeDelta(v, opponents) {
  * @param {{ tau: number; }} options
  */
 function volF(phi, v, delta, a, options) {
-  var phi2 = Math.pow(phi, 2);
-  var d2 = Math.pow(delta, 2);
+  const phi2 = Math.pow(phi, 2);
+  const d2 = Math.pow(delta, 2);
 
   /**
    * @param {number} x
    */
   return function(x) {
-    var ex = Math.exp(x);
-    var a2 = phi2 + v + ex;
-    var p2 = (x - a) / Math.pow(options.tau, 2);
-    var p1 = (ex * (d2 - phi2 - v - ex)) / (2 * Math.pow(a2, 2));
+    const ex = Math.exp(x);
+    const a2 = phi2 + v + ex;
+    const p2 = (x - a) / Math.pow(options.tau, 2);
+    const p1 = (ex * (d2 - phi2 - v - ex)) / (2 * Math.pow(a2, 2));
     return p1 - p2;
   };
 }
@@ -117,32 +115,32 @@ function volF(phi, v, delta, a, options) {
  */
 function computeVolatility(sigma, phi, v, delta, options) {
   // 5.1
-  var a = Math.log(Math.pow(sigma, 2));
-  var f = volF(phi, v, delta, a, options);
+  let a = Math.log(Math.pow(sigma, 2));
+  const f = volF(phi, v, delta, a, options);
 
   // 5.2
   /** @type {number} */
-  var b;
+  let b;
   if (Math.pow(delta, 2) > Math.pow(phi, 2) + v) {
     b = Math.log(Math.pow(delta, 2) - Math.pow(phi, 2) - v);
   }
   else {
-    var k = 1;
+    let k = 1;
     while (f(a - k * options.tau) < 0) {
       k++;
     }
     b = a - k * options.tau;
   }
 
   // 5.3
-  var fa = f(a);
-  var fb = f(b);
+  let fa = f(a);
+  let fb = f(b);
 
   // 5.4
   while (Math.abs(b - a) > 0.000001) {
     /** @type {number} */
-    var c = a + (a - b) * fa / (fb - fa);
-    var fc = f(c);
+    const c = a + (a - b) * fa / (fb - fa);
+    const fc = f(c);
 
     if (fc * fb < 0) {
       a = b;
@@ -176,10 +174,11 @@ function phiStar(sigmap, phi) {
  * @param {readonly ScaledOpponent[]} opponents
  */
 function newRating(phis, mu, v, opponents) {
-  var phip = 1 / Math.sqrt(1 / Math.pow(phis, 2) + 1 / v);
-  var mup = mu + Math.pow(phip, 2) * reduce(opponents, function(sum, opp) {
-    return sum + opp.gphij * (opp.score - opp.emmp);
-  }, 0);
+  const phip = 1 / Math.sqrt(1 / Math.pow(phis, 2) + 1 / v);
+  const mup = mu + Math.pow(phip, 2) * opponents.reduce(
+    (sum, opp) => sum + opp.gphij * (opp.score - opp.emmp),
+    0
+  );
   return { mu: mup, phi: phip };
 }
 
@@ -189,9 +188,9 @@ function newRating(phis, mu, v, opponents) {
  * @param {{ rating: number; }} options
  */
 function unscale(mup, phip, options) {
-  var rating = 173.7178 * mup + options.rating;
-  var rd = 173.7178 * phip;
-  return { rating: rating, rd: rd };
+  const rating = 173.7178 * mup + options.rating;
+  const rd = 173.7178 * phip;
+  return { rating, rd };
 }
 
 /**
@@ -204,28 +203,32 @@ function unscale(mup, phip, options) {
  */
 function rate(rating, rd, sigma, opponents, options) {
   /** @type {{ rating: number; tau: number; }} */
-  var opts = assign({}, { rating: 1500, tau: 0.5 }, options || {});
+  const opts = Object.assign({}, { rating: 1500, tau: 0.5 }, options || {});
 
   // Step 2
-  var scaled = scale(rating, rd, opts);
-  var scaledOpponents = scaleOpponents(scaled.mu, opponents, opts);
+  const scaled = scale(rating, rd, opts);
+  const scaledOpponents = scaleOpponents(scaled.mu, opponents, opts);
 
   // Step 3
-  var v = updateRating(scaledOpponents);
+  const v = updateRating(scaledOpponents);
 
   // Step 4
-  var delta = computeDelta(v, scaledOpponents);
+  const delta = computeDelta(v, scaledOpponents);
 
   // Step 5
-  var sigmap = computeVolatility(sigma, scaled.phi, v, delta, opts);
+  const sigmap = computeVolatility(sigma, scaled.phi, v, delta, opts);
 
   // Step 6
-  var phis = phiStar(sigmap, scaled.phi);
+  const phis = phiStar(sigmap, scaled.phi);
 
   // Step 7
-  var updated = newRating(phis, scaled.mu, v, scaledOpponents);
+  const updated = newRating(phis, scaled.mu, v, scaledOpponents);
 
-  return assign({}, unscale(updated.mu, updated.phi, opts), { vol: sigmap });
+  return Object.assign(
+    {},
+    unscale(updated.mu, updated.phi, opts),
+    { vol: sigmap }
+  );
 }
 
 module.exports = rate;

package.json

@@ -10,7 +10,7 @@
   "author": "Kenan Yildirim <kenan@kenany.me> (https://kenany.me/)",
   "main": "index.js",
   "engines": {
-    "node": "12 || 14 || 16 || >=18"
+    "node": "14 || 16 || >=18"
   },
   "files": [
     "CHANGELOG.md",
@@ -29,27 +29,20 @@
     "posttest": "npm run -s lint",
     "lint": "eslint index.js test/index.js bench/index.js"
   },
-  "dependencies": {
-    "lodash.assign": "^4.2.0",
-    "lodash.map": "^4.6.0",
-    "lodash.reduce": "^4.6.0"
-  },
+  "dependencies": {},
   "devDependencies": {
-    "@kenan/eslint-config": "^9.0.4",
+    "@kenan/eslint-config": "^10.0.1",
     "@semantic-release/changelog": "^6.0.1",
     "@semantic-release/git": "^10.0.1",
-    "@tsconfig/node12": "^1.0.11",
+    "@tsconfig/node14": "^1.0.3",
     "@types/almost-equal": "^1.1.0",
-    "@types/lodash.assign": "^4.2.7",
     "@types/lodash.isfunction": "^3.0.7",
-    "@types/lodash.map": "^4.6.13",
-    "@types/lodash.reduce": "^4.6.7",
     "@types/tape": "^4.13.2",
     "almost-equal": "^1.1.0",
     "beautify-benchmark": "^0.2.4",
     "benchmark": "^2.1.4",
     "conventional-changelog-conventionalcommits": "^5.0.0",
-    "eslint": "^7.32.0",
+    "eslint": "^8.27.0",
     "glicko2": "^1.0.0",
     "lodash.isfunction": "^3.0.9",
     "semantic-release": "^19.0.5",

test/index.js

@@ -1,23 +1,23 @@
 'use strict';
 
-var test = require('tape');
-var isFunction = require('lodash.isfunction');
-var almostEqual = require('almost-equal');
+const test = require('tape');
+const isFunction = require('lodash.isfunction');
+const almostEqual = require('almost-equal');
 
-var glicko2 = require('../');
+const glicko2 = require('../');
 
-test('exports a function', function(t) {
+test('exports a function', (t) => {
   t.plan(1);
   t.ok(isFunction(glicko2));
 });
 
-test('calculates new ratings', function(t) {
+test('calculates new ratings', (t) => {
   t.plan(3);
 
-  var a = { rating: 1500, rd: 200, vol: 0.06 };
-  var b = { rating: 1400, rd: 30, vol: 0.06 };
-  var c = { rating: 1550, rd: 100, vol: 0.06 };
-  var d = { rating: 1700, rd: 300, vol: 0.06 };
+  let a = { rating: 1500, rd: 200, vol: 0.06 };
+  const b = { rating: 1400, rd: 30, vol: 0.06 };
+  const c = { rating: 1550, rd: 100, vol: 0.06 };
+  const d = { rating: 1700, rd: 300, vol: 0.06 };
 
   // a beats b
   // c beats a

tsconfig.json

@@ -1,5 +1,5 @@
 {
-  "extends": "@tsconfig/node12/tsconfig.json",
+  "extends": "@tsconfig/node14/tsconfig.json",
   "compilerOptions": {
     "allowJs": true,
     "checkJs": true,