lint

eslint.config.js

@@ -10,4 +10,12 @@ export default [
   ...typescript.configs.recommended,
   prettier,
   { languageOptions: { globals: globals.browser } },
+  {
+    rules: {
+      'prefer-const': ['error', { destructuring: 'all' }],
+      'prefer-template': 'error',
+      'array-callback-return': 'error',
+      'no-useless-assignment': 'error',
+    },
+  },
 ];

src/2015/day07.js

@@ -17,7 +17,7 @@ function makeCircuit(input) {
       x.match(/^(?:(\w+) )?(?:(AND|OR|NOT|LSHIFT|RSHIFT) (\w+) )?-> (\w+)$/),
     )
     .map(x => ({
-      op: ops[x[2] + ''],
+      op: ops[`${x[2]}`],
       p1: getter(x[1]),
       p2: getter(x[3]),
       result: x[4],

src/2015/day10.js

@@ -1,7 +1,7 @@
 function transform(s) {
   return s
     .match(/(.)\1*/g)
-    .map(x => x.length + '' + x[0])
+    .map(x => `${x.length}${x[0]}`)
     .join('');
 }
 

src/2016/day17.js

@@ -2,10 +2,10 @@ import md5 from '../utils/md5.js';
 
 function getNeighbors(point, [U, D, L, R]) {
   return [
-    U && { x: point.x, y: point.y - 1, path: point.path + 'U' },
-    D && { x: point.x, y: point.y + 1, path: point.path + 'D' },
-    L && { x: point.x - 1, y: point.y, path: point.path + 'L' },
-    R && { x: point.x + 1, y: point.y, path: point.path + 'R' },
+    U && { x: point.x, y: point.y - 1, path: `${point.path}U` },
+    D && { x: point.x, y: point.y + 1, path: `${point.path}D` },
+    L && { x: point.x - 1, y: point.y, path: `${point.path}L` },
+    R && { x: point.x + 1, y: point.y, path: `${point.path}R` },
   ].filter(p => p && p.x >= 0 && p.y >= 0 && p.x <= 3 && p.y <= 3);
 }
 

src/2018/day12.js

@@ -31,7 +31,7 @@ function transform(current, transformations, memo, i) {
     return recall(current, memo, i);
   }
   current.start -= 5;
-  current.state = '.....' + current.state + '.....';
+  current.state = `.....${current.state}.....`;
   const next = { start: current.start, state: '..' };
   for (let i = 0; i < current.state.length - 5; i++) {
     if (transformations[current.state.slice(i, i + 5)] === '#') {

src/2018/day15.js

@@ -85,7 +85,7 @@ function fight(input, elfBoost = 0) {
 
 export function part1(input) {
   const { i, units } = fight(input);
-  return i * units.reduce((sum, u) => (sum += u.hit), 0);
+  return i * units.reduce((sum, u) => sum + u.hit, 0);
 }
 
 export function part2(input) {
@@ -96,5 +96,5 @@ export function part2(input) {
     ({ i, units } = fight(input, elfBoost));
     elfBoost++;
   } while (elfCount !== count(units, 'E'));
-  return i * units.reduce((sum, u) => (sum += u.hit), 0);
+  return i * units.reduce((sum, u) => sum + u.hit, 0);
 }

src/2019/day17.js

@@ -101,7 +101,7 @@ export function part1(input) {
 export function part2(input) {
   const map = createMap(input);
   const route = findRoute(map).join(',');
-  const [, A, B, C] = (route + ',').match(
+  const [, A, B, C] = `${route},`.match(
     /^(.{1,20}),(?:\1,)*(.{1,20}),(?:\1,|\2,)*(.{1,20}),(?:\1,|\2,|\3,)*$/,
   );
   const main = route

src/2020/day11.js

@@ -24,7 +24,7 @@ function neighbors(seats, current, far) {
 function life(input, count, far) {
   let seats = input.split('\n').map(x => x.split(''));
   let occupied = 0;
-  let prev = 0;
+  let prev;
   do {
     seats = seats.map((line, y) =>
       line.map((seat, x) => {

src/2020/day17.js

@@ -20,8 +20,8 @@ function neighbors(key) {
 
 export function part1(input, dimensions = 3) {
   const map = new Map();
-  input.split('\n').map((line, y) => {
-    line.split('').map((char, x) => {
+  input.split('\n').forEach((line, y) => {
+    line.split('').forEach((char, x) => {
       const coordinates = new Array(dimensions - 2).fill(0);
       map.set([x, y, ...coordinates].join(','), char === '#');
     });

src/2022/day12.js

@@ -32,7 +32,7 @@ export function part2(input) {
   const str = input.replace('S', 'a');
   let min = Infinity;
   for (const { index } of str.matchAll(/a/g)) {
-    const result = part1(str.slice(0, index) + 'S' + str.slice(index + 1));
+    const result = part1(`${str.slice(0, index)}S${str.slice(index + 1)}`);
     min = result < min ? result : min;
   }
   return min;

src/2022/day21.js

@@ -10,7 +10,7 @@ function parse(input) {
           /^([a-z]+): ([a-z]+) (.) ([a-z]+)$/,
         );
         return { variable, param1, operator, param2 };
-      }
+      } else return undefined;
     })
     .reduce((obj, x) => ({ ...obj, [x.variable]: x }), {});
 }

src/2023/day18.js

@@ -27,9 +27,9 @@ export function part1(input) {
 
 export function part2(input) {
   const lines = input.split('\n').map(line => {
-    let [direction, count, color] = line.split(' ');
-    count = parseInt(color.slice(2, -2), 16);
-    direction = 'RDLU'.at(color.slice(-2, -1));
+    const [, , color] = line.split(' ');
+    const count = parseInt(color.slice(2, -2), 16);
+    const direction = 'RDLU'.at(color.slice(-2, -1));
     return { direction, count };
   });
   return solve(lines);