diff --git a/.github/workflows/typedoc.yml b/.github/workflows/typedoc.yml
index 881ec7f..81c1ff6 100644
--- a/.github/workflows/typedoc.yml
+++ b/.github/workflows/typedoc.yml
@@ -1,32 +1,15 @@
-name: Deploy TypeDoc on GitHub pages
+name: TypeDoc
 
 on:
   workflow_dispatch:
   release:
     types: [published]
 
-env:
-  NODE_VERSION: 20.x
-  ENTRY_FILE: 'src/index.ts'
-
 jobs:
-  deploy:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v3
-      - uses: actions/setup-node@v3
-        with:
-          node-version: ${{ env.NODE_VERSION }}
-      - name: Install dependencies
-        run: npm install
-      - name: Build documentation
-        uses: zakodium/typedoc-action@v2
-        with:
-          entry: ${{ env.ENTRY_FILE }}
-      - name: Deploy to GitHub pages
-        uses: JamesIves/github-pages-deploy-action@releases/v4
-        with:
-          token: ${{ secrets.BOT_TOKEN }}
-          branch: gh-pages
-          folder: docs
-          clean: true
+  typedoc:
+    # Documentation: https://github.com/zakodium/workflows#typedoc
+    uses: zakodium/workflows/.github/workflows/typedoc.yml@typedoc-v1
+    with:
+      entry: 'src/index.ts'
+    secrets:
+      github-token: ${{ secrets.BOT_TOKEN }}
diff --git a/.gitignore b/.gitignore
index b2c0bef..b942be8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -37,6 +37,5 @@ jspm_packages
 .node_repl_history
 
 lib
-
-lib-esm
 docs
+.claude
diff --git a/eslint.config.mjs b/eslint.config.mjs
index 5935144..889a2e4 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -1,4 +1,4 @@
 import { defineConfig, globalIgnores } from 'eslint/config';
 import ts from 'eslint-config-cheminfo-typescript/base';
 
-export default defineConfig(globalIgnores(['coverage', 'lib', 'lib-esm']), ts);
+export default defineConfig(globalIgnores(['coverage', 'lib']), ts);
diff --git a/package.json b/package.json
index e5be536..af422d4 100644
--- a/package.json
+++ b/package.json
@@ -2,28 +2,27 @@
   "name": "ml-regression-base",
   "version": "4.0.1",
   "description": "Base class for regression modules",
-  "main": "./lib/index.js",
-  "module": "./lib-esm/index.js",
-  "types": "./lib/index.d.ts",
+  "type": "module",
+  "exports": {
+    ".": "./lib/index.js"
+  },
   "sideEffects": false,
   "files": [
-    "src",
     "lib",
-    "lib-esm"
+    "src"
   ],
   "scripts": {
     "check-types": "tsc --noEmit",
-    "clean": "rimraf lib lib-esm",
+    "clean": "rimraf lib",
     "eslint": "eslint src",
     "eslint-fix": "npm run eslint -- --fix",
     "prepack": "npm run tsc",
     "prettier": "prettier --check src",
     "prettier-write": "prettier --write src",
-    "test": "npm run test-only && npm run eslint && npm run prettier && npm run check-types",
+    "test": "npm run test-only && npm run check-types && npm run eslint && npm run prettier",
     "test-only": "vitest run --coverage",
-    "tsc": "npm run clean && npm run tsc-cjs && npm run tsc-esm",
-    "tsc-cjs": "tsc --project tsconfig.cjs.json",
-    "tsc-esm": "tsc --project tsconfig.esm.json"
+    "tsc": "npm run clean && npm run tsc-build",
+    "tsc-build": "tsc --project tsconfig.build.json"
   },
   "repository": {
     "type": "git",
@@ -41,7 +40,9 @@
     "is-any-array": "^3.0.0"
   },
   "devDependencies": {
+    "@types/node": "^25.6.0",
     "@vitest/coverage-v8": "^4.1.4",
+    "@zakodium/tsconfig": "^1.0.5",
     "eslint": "^9.39.4",
     "eslint-config-cheminfo-typescript": "^22.0.0",
     "prettier": "^3.8.3",
diff --git a/src/BaseRegression.ts b/src/BaseRegression.ts
index ddd8026..bd98175 100644
--- a/src/BaseRegression.ts
+++ b/src/BaseRegression.ts
@@ -1,7 +1,7 @@
 import type { NumberArray } from 'cheminfo-types';
 import { isAnyArray } from 'is-any-array';
 
-import { checkArrayLength } from './checkArrayLength';
+import { checkArrayLength } from './checkArrayLength.ts';
 
 export interface RegressionScore {
   r: number;
@@ -9,6 +9,7 @@ export interface RegressionScore {
   chi2: number;
   rmsd: number;
 }
+
 export class BaseRegression {
   constructor() {
     if (new.target === BaseRegression) {
@@ -55,7 +56,7 @@ export class BaseRegression {
    * Return the correlation coefficient of determination (r) and chi-square.
    * @param x - explanatory variable
    * @param y - response variable
-   * @return - Object with further statistics.
+   * @returns Object with further statistics.
    */
   score(x: NumberArray, y: NumberArray): RegressionScore {
     checkArrayLength(x, y);
@@ -63,7 +64,7 @@ export class BaseRegression {
     const n = x.length;
     const y2: number[] = new Array(n);
     for (let i = 0; i < n; i++) {
-      y2[i] = this._predict(x[i]);
+      y2[i] = this._predict(x[i] as number);
     }
 
     let xSum = 0;
@@ -74,15 +75,17 @@ export class BaseRegression {
     let ySquared = 0;
     let xY = 0;
     for (let i = 0; i < n; i++) {
-      xSum += y2[i];
-      ySum += y[i];
-      xSquared += y2[i] * y2[i];
-      ySquared += y[i] * y[i];
-      xY += y2[i] * y[i];
-      if (y[i] !== 0) {
-        chi2 += ((y[i] - y2[i]) * (y[i] - y2[i])) / y[i];
+      const yi = y[i] as number;
+      const y2i = y2[i] as number;
+      xSum += y2i;
+      ySum += yi;
+      xSquared += y2i * y2i;
+      ySquared += yi * yi;
+      xY += y2i * yi;
+      if (yi !== 0) {
+        chi2 += ((yi - y2i) * (yi - y2i)) / yi;
       }
-      rmsd += (y[i] - y2[i]) * (y[i] - y2[i]);
+      rmsd += (yi - y2i) * (yi - y2i);
     }
 
     const r =
diff --git a/src/__tests__/BaseRegression.test.ts b/src/__tests__/BaseRegression.test.ts
index 01aebf1..350c848 100644
--- a/src/__tests__/BaseRegression.test.ts
+++ b/src/__tests__/BaseRegression.test.ts
@@ -1,6 +1,6 @@
-import { describe, expect, it } from 'vitest';
+import { expect, test } from 'vitest';
 
-import { BaseRegression } from '..';
+import { BaseRegression } from '../index.ts';
 
 class NoPredict extends BaseRegression {}
 class Basic extends BaseRegression {
@@ -9,82 +9,86 @@ class Basic extends BaseRegression {
     super();
     this.factor = factor;
   }
-  _predict(x: number) {
+  override _predict(x: number) {
     return x * this.factor;
   }
 }
 
-describe('base regression', () => {
-  it('should not be directly constructable', () => {
-    expect(() => {
-      // eslint-disable-next-line no-new
-      new BaseRegression();
-    }).toThrow(/BaseRegression must be subclassed/);
-  });
+test('should not be directly constructable', () => {
+  expect(() => {
+    // eslint-disable-next-line no-new
+    new BaseRegression();
+  }).toThrow(/BaseRegression must be subclassed/);
+});
 
-  it('should throw if _predict is not implemented', () => {
-    const reg = new NoPredict();
-    expect(() => {
-      reg.predict(0);
-    }).toThrow(/_predict must be implemented/);
-  });
+test('should throw if _predict is not implemented', () => {
+  const reg = new NoPredict();
 
-  it('should do a basic prediction', () => {
-    const basic = new Basic(2);
-    expect(basic.predict(1)).toBe(2);
-    expect(basic.predict(2)).toBe(4);
-    expect(basic.predict([2, 3])).toStrictEqual([4, 6]);
-  });
+  expect(() => {
+    reg.predict(0);
+  }).toThrow(/_predict must be implemented/);
+});
+
+test('should do a basic prediction', () => {
+  const basic = new Basic(2);
+
+  expect(basic.predict(1)).toBe(2);
+  expect(basic.predict(2)).toBe(4);
+  expect(basic.predict([2, 3])).toStrictEqual([4, 6]);
+});
+
+test('should throw on invalid value', () => {
+  const basic = new Basic(2);
 
-  it('should throw on invalid value', () => {
-    const basic = new Basic(2);
-    expect(() => {
-      // @ts-expect-error testing invalid input
-      basic.predict();
-    }).toThrow(/must be a number or array/);
+  expect(() => {
+    // @ts-expect-error testing invalid input
+    basic.predict();
+  }).toThrow(/must be a number or array/);
+});
+
+test('should implement dummy predictor functions', () => {
+  const basic = new Basic(2);
+  basic.train(); // should not throw
+
+  expect(basic.toString()).toBe('');
+  expect(basic.toLaTeX()).toBe('');
+});
+
+test('should implement a scoring function', () => {
+  const basic = new Basic(2);
+
+  expect(basic.score([1, 2], [2, 4])).toStrictEqual({
+    r: 1,
+    r2: 1,
+    chi2: 0,
+    rmsd: 0,
   });
+  expect(basic.score([1, 2], [2, 4.1]).rmsd).toBe(0.0707106781186545);
 
-  it('should implement dummy predictor functions', () => {
-    const basic = new Basic(2);
-    basic.train(); // should not throw
-    expect(basic.toString()).toBe('');
-    expect(basic.toLaTeX()).toBe('');
+  expect(basic.score([1, 2], [0.5, 2])).toStrictEqual({
+    r: 1,
+    r2: 1,
+    chi2: 6.5,
+    rmsd: 1.7677669529663689,
   });
 
-  it('should implement a scoring function', () => {
-    const basic = new Basic(2);
-    expect(basic.score([1, 2], [2, 4])).toStrictEqual({
-      r: 1,
-      r2: 1,
-      chi2: 0,
-      rmsd: 0,
-    });
-    expect(basic.score([1, 2], [2, 4.1]).rmsd).toBe(0.0707106781186545);
-
-    expect(basic.score([1, 2], [0.5, 2])).toStrictEqual({
-      r: 1,
-      r2: 1,
-      chi2: 6.5,
-      rmsd: 1.7677669529663689,
-    });
-
-    expect(basic.score([1, 2], [0, 1])).toStrictEqual({
-      r: 1,
-      r2: 1,
-      chi2: 9,
-      rmsd: 2.5495097567963922,
-    });
+  expect(basic.score([1, 2], [0, 1])).toStrictEqual({
+    r: 1,
+    r2: 1,
+    chi2: 9,
+    rmsd: 2.5495097567963922,
   });
+});
 
-  it('should throw error if inputs are not arrays or has different length', () => {
-    const basic = new Basic(2);
-    expect(() => {
-      // @ts-expect-error testing invalid input
-      basic.score(1, 2);
-    }).toThrow('x and y must be arrays');
+test('should throw error if inputs are not arrays or has different length', () => {
+  const basic = new Basic(2);
 
-    expect(() => {
-      basic.score([1, 2], [2]);
-    }).toThrow('x and y arrays must have the same length');
-  });
+  expect(() => {
+    // @ts-expect-error testing invalid input
+    basic.score(1, 2);
+  }).toThrow('x and y must be arrays');
+
+  expect(() => {
+    basic.score([1, 2], [2]);
+  }).toThrow('x and y arrays must have the same length');
 });
diff --git a/src/__tests__/checkArrayLength.test.ts b/src/__tests__/checkArrayLength.test.ts
index a30ecf7..53b8f71 100644
--- a/src/__tests__/checkArrayLength.test.ts
+++ b/src/__tests__/checkArrayLength.test.ts
@@ -1,34 +1,34 @@
-import { describe, expect, it } from 'vitest';
+import { expect, test } from 'vitest';
 
-import { checkArrayLength } from '..';
+import { checkArrayLength } from '../index.ts';
 
-describe('checkArrayLength', () => {
-  it('throws on different Length', () => {
-    const expected = /x and y arrays must have the same length/;
-    expect(() => checkArrayLength([], [1])).toThrow(expected);
-    expect(() => checkArrayLength([1], [])).toThrow(expected);
-    expect(() => checkArrayLength([1], [1, 2])).toThrow(expected);
-  });
+test('throws on different Length', () => {
+  const expected = /x and y arrays must have the same length/;
 
-  it('throws if not arrays', () => {
-    const expected = /x and y must be arrays/;
-    // @ts-expect-error testing invalid input
-    expect(() => checkArrayLength(null, [1])).toThrow(expected);
-    // @ts-expect-error testing invalid input
-    expect(() => checkArrayLength([], null)).toThrow(expected);
-    // @ts-expect-error testing invalid input
-    expect(() => checkArrayLength()).toThrow(expected);
-    // @ts-expect-error testing invalid input
-    expect(() => checkArrayLength(42, [])).toThrow(expected);
-    // @ts-expect-error testing invalid input
-    expect(() => checkArrayLength([1, 2, 3, 4, 5], 'hello')).toThrow(expected);
-  });
+  expect(() => checkArrayLength([], [1])).toThrow(expected);
+  expect(() => checkArrayLength([1], [])).toThrow(expected);
+  expect(() => checkArrayLength([1], [1, 2])).toThrow(expected);
+});
+
+test('throws if not arrays', () => {
+  const expected = /x and y must be arrays/;
+
+  // @ts-expect-error testing invalid input
+  expect(() => checkArrayLength(null, [1])).toThrow(expected);
+  // @ts-expect-error testing invalid input
+  expect(() => checkArrayLength([], null)).toThrow(expected);
+  // @ts-expect-error testing invalid input
+  expect(() => checkArrayLength()).toThrow(expected);
+  // @ts-expect-error testing invalid input
+  expect(() => checkArrayLength(42, [])).toThrow(expected);
+  // @ts-expect-error testing invalid input
+  expect(() => checkArrayLength([1, 2, 3, 4, 5], 'hello')).toThrow(expected);
+});
 
-  it('correct result', () => {
-    expect(checkArrayLength([1, 2], [2, 3])).toBeUndefined();
-    expect(
-      checkArrayLength(new Float64Array([1, 2]), new Float64Array([2, 3])),
-    ).toBeUndefined();
-    expect(checkArrayLength([1, 2], new Float64Array([2, 3]))).toBeUndefined();
-  });
+test('correct result', () => {
+  expect(checkArrayLength([1, 2], [2, 3])).toBeUndefined();
+  expect(
+    checkArrayLength(new Float64Array([1, 2]), new Float64Array([2, 3])),
+  ).toBeUndefined();
+  expect(checkArrayLength([1, 2], new Float64Array([2, 3]))).toBeUndefined();
 });
diff --git a/src/__tests__/maybeToPrecision.test.ts b/src/__tests__/maybeToPrecision.test.ts
index 1ca46d9..21bd310 100644
--- a/src/__tests__/maybeToPrecision.test.ts
+++ b/src/__tests__/maybeToPrecision.test.ts
@@ -1,36 +1,34 @@
-import { describe, expect, it } from 'vitest';
+import { expect, test } from 'vitest';
 
-import { maybeToPrecision } from '..';
+import { maybeToPrecision } from '../index.ts';
 
-describe('maybeToPrecision', () => {
-  it('positive number - no digit', () => {
-    expect(maybeToPrecision(0)).toBe('0');
-    expect(maybeToPrecision(10)).toBe('10');
-    expect(maybeToPrecision(0.052469)).toBe('0.052469');
-  });
+test('positive number - no digit', () => {
+  expect(maybeToPrecision(0)).toBe('0');
+  expect(maybeToPrecision(10)).toBe('10');
+  expect(maybeToPrecision(0.052469)).toBe('0.052469');
+});
 
-  it('positive number - digit', () => {
-    expect(maybeToPrecision(0, 1)).toBe('0');
-    expect(maybeToPrecision(0, 2)).toBe('0.0');
-    expect(maybeToPrecision(0.52469, 3)).toBe('0.525');
-  });
+test('positive number - digit', () => {
+  expect(maybeToPrecision(0, 1)).toBe('0');
+  expect(maybeToPrecision(0, 2)).toBe('0.0');
+  expect(maybeToPrecision(0.52469, 3)).toBe('0.525');
+});
 
-  it('negative number - no digit', () => {
-    expect(maybeToPrecision(-0)).toBe('0');
-    expect(maybeToPrecision(-10)).toBe('- 10');
-    expect(maybeToPrecision(-0.052469)).toBe('- 0.052469');
-  });
+test('negative number - no digit', () => {
+  expect(maybeToPrecision(-0)).toBe('0');
+  expect(maybeToPrecision(-10)).toBe('- 10');
+  expect(maybeToPrecision(-0.052469)).toBe('- 0.052469');
+});
 
-  it('negative number - digit', () => {
-    expect(maybeToPrecision(-0, 1)).toBe('0');
-    expect(maybeToPrecision(-0, 2)).toBe('0.0');
-    expect(maybeToPrecision(-0.52469, 3)).toBe('- 0.525');
-    expect(maybeToPrecision(-4, 3)).toBe('- 4.00');
-  });
+test('negative number - digit', () => {
+  expect(maybeToPrecision(-0, 1)).toBe('0');
+  expect(maybeToPrecision(-0, 2)).toBe('0.0');
+  expect(maybeToPrecision(-0.52469, 3)).toBe('- 0.525');
+  expect(maybeToPrecision(-4, 3)).toBe('- 4.00');
+});
 
-  it('wrong digit option', () => {
-    expect(() => {
-      maybeToPrecision(0, 0);
-    }).toThrow(/toPrecision\(\) argument must be between 1 and (?:100|21)/);
-  });
+test('wrong digit option', () => {
+  expect(() => {
+    maybeToPrecision(0, 0);
+  }).toThrow(/toPrecision\(\) argument must be between 1 and (?:100|21)/);
 });
diff --git a/src/checkArrayLength.ts b/src/checkArrayLength.ts
index 84a1a11..caf6843 100644
--- a/src/checkArrayLength.ts
+++ b/src/checkArrayLength.ts
@@ -1,10 +1,12 @@
 import type { NumberArray } from 'cheminfo-types';
 import { isAnyArray } from 'is-any-array';
+
 /**
  * Check that x and y are arrays with the same length.
  * @param x - first array
  * @param y - second array
- * @throws if x or y are not the same length, or if they are not arrays
+ * @throws {TypeError} if x or y are not arrays.
+ * @throws {RangeError} if x and y do not have the same length.
  */
 export function checkArrayLength(x: NumberArray, y: NumberArray) {
   if (!isAnyArray(x) || !isAnyArray(y)) {
diff --git a/src/index.ts b/src/index.ts
index 0175194..509e0ca 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,3 +1,3 @@
-export * from './BaseRegression';
-export * from './checkArrayLength';
-export * from './maybeToPrecision';
+export * from './BaseRegression.ts';
+export * from './checkArrayLength.ts';
+export * from './maybeToPrecision.ts';
diff --git a/src/maybeToPrecision.ts b/src/maybeToPrecision.ts
index 24afffc..3b1c902 100644
--- a/src/maybeToPrecision.ts
+++ b/src/maybeToPrecision.ts
@@ -1,8 +1,8 @@
 /**
  * Cast `number` to string. Optionally `digits` specifies significant figures.
- * @param number
- * @param figures
- * @returns - A string representation of `number`.
+ * @param number - The number to convert.
+ * @param figures - Number of significant figures.
+ * @returns A string representation of `number`.
  */
 export function maybeToPrecision(number: number, figures?: number) {
   if (number < 0) {
diff --git a/tsconfig.build.json b/tsconfig.build.json
new file mode 100644
index 0000000..d55545e
--- /dev/null
+++ b/tsconfig.build.json
@@ -0,0 +1,8 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src"
+  },
+  "include": ["src"],
+  "exclude": ["**/__tests__", "**/*.test.*"]
+}
diff --git a/tsconfig.cjs.json b/tsconfig.cjs.json
deleted file mode 100644
index 9ea4847..0000000
--- a/tsconfig.cjs.json
+++ /dev/null
@@ -1,12 +0,0 @@
-{
-  "extends": "./tsconfig.json",
-  "compilerOptions": {
-    "rootDir": "./src",
-    "module": "commonjs",
-    "declaration": true,
-    "declarationMap": true
-  },
-  "exclude": [
-    "./src/**/__tests__"
-  ]
-}
diff --git a/tsconfig.esm.json b/tsconfig.esm.json
deleted file mode 100644
index 050b45d..0000000
--- a/tsconfig.esm.json
+++ /dev/null
@@ -1,7 +0,0 @@
-{
-  "extends": "./tsconfig.cjs.json",
-  "compilerOptions": {
-    "module": "es2020",
-    "outDir": "lib-esm"
-  }
-}
diff --git a/tsconfig.json b/tsconfig.json
index 59aea42..5964c49 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,14 +1,9 @@
 {
+  "extends": "@zakodium/tsconfig",
   "compilerOptions": {
-    "allowJs": true,
-    "esModuleInterop": true,
-    "moduleResolution": "node",
+    "noUncheckedIndexedAccess": true,
     "outDir": "lib",
-    "sourceMap": true,
-    "skipLibCheck": true,
-    "strict": true,
-    "target": "es2020",
-    "ignoreDeprecations": "6.0"
+    "types": ["node"]
   },
-  "include": ["./src/**/*"]
+  "include": ["src", "vite*.ts"]
 }
diff --git a/vitest.config.ts b/vitest.config.ts
new file mode 100644
index 0000000..7ed5e86
--- /dev/null
+++ b/vitest.config.ts
@@ -0,0 +1,9 @@
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    snapshotFormat: {
+      maxOutputLength: Number.MAX_SAFE_INTEGER,
+    },
+  },
+});