typescriptify the whole shabang

jest.config.js

@@ -0,0 +1,5 @@
+/** @type {import('ts-jest').JestConfigWithTsJest} */
+export default {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+};

package.json

@@ -4,9 +4,9 @@
   "type": "module",
   "description": "Validation for Norwegian national id numbers (\"fødselsnummer\" and \"d-nummer\")",
   "scripts": {
-    "build": "babel src -d dist",
-    "test": "mocha --reporter spec tests/",
-    "test-w": "mocha --watch --reporter spec tests/"
+    "build": "tsc",
+    "test": "jest",
+    "test-w": "jest --watch"
   },
   "author": "NAV (https://nav.no)",
   "license": "MIT",
@@ -18,13 +18,18 @@
     "url": "https://github.com/navikt/fnrvalidator/issues"
   },
   "main": "dist/validator.js",
-  "typings": "fnrvalidator.d.ts",
+  "typings": "dist/validator.d.ts",
   "devDependencies": {
     "@babel/cli": "^7.17.10",
     "@babel/core": "^7.24.0",
     "@babel/preset-env": "^7.24.0",
+    "@types/jest": "^29.5.12",
     "caniuse-lite": "^1.0.30001596",
-    "chai": "5.1.0",
-    "mocha": "10.3.0"
+    "jest": "^29.7.0",
+    "ts-jest": "^29.1.2",
+    "ts-node": "^10.9.2"
+  },
+  "dependencies": {
+    "typescript": "^5.4.2"
   }
 }

src/validator.ts

@@ -0,0 +1,108 @@
+'use strict'
+
+type LENGTH_ERROR = 'fnr, dnr or hnr must consist of 11 digits';
+type CHECKSUM_ERROR = "checksums don't match";
+type DATE_ERROR = 'invalid date';
+type ErrorReason = LENGTH_ERROR | CHECKSUM_ERROR | DATE_ERROR;
+type OkResult = { status: 'valid'; type: NrType };
+type NrType = 'dnr' | 'fnr' | 'hnr' | 'tnr' | 'dnr-and-hnr'
+type ErrorResult = { status: 'invalid'; reasons: ErrorReason[] };
+type ValidationResult = OkResult | ErrorResult;
+
+const elevenDigits = new RegExp('^\\d{11}$')
+
+export const fnr = (digits: string): ValidationResult => {
+   return idnr(digits)
+}
+
+export const dnr = (digits: string): ValidationResult => {
+   return idnr(digits)
+}
+
+export const hnr = (digits: string): ValidationResult => {
+   return idnr(digits)
+}
+
+export const tnr = (digits: string): ValidationResult => {
+   return idnr(digits)
+}
+
+export const dnrAndHnr = (digits: string): ValidationResult => {
+   return idnr(digits)
+}
+
+export const getType = (digits: string): NrType => {
+   let nrs = digits.split("").map(Number)
+   if (nrs[0] >= 4 && nrs[2] >= 4) {
+      return 'dnr-and-hnr'
+   }
+   else if (nrs[0] >= 4) {
+      return 'dnr'
+   } else if (nrs[2] >= 8) {
+      return "tnr"
+   } else if (nrs[2] >= 4) {
+      return 'hnr'
+   }
+   return 'fnr'
+}
+
+export const idnr = (digits: string): ValidationResult => {
+   const type = getType(digits)
+   return validate(digits, type)
+}
+
+const validate = (digits: string, type: NrType): ValidationResult => {
+   if (!elevenDigits.test(digits)) {
+      return {
+         status: "invalid",
+         reasons: ["fnr, dnr or hnr must consist of 11 digits"]
+      }
+   }
+
+   const errMsgs = [...checksums(digits), ...birthdate(digits, type)]
+
+   return errMsgs.length == 0 ? {status: "valid", type} :
+      {
+         status: "invalid",
+         reasons: errMsgs
+      }
+}
+
+const checksums = (digits: string): Array<CHECKSUM_ERROR> => {
+   let nrs = digits.split("").map(Number)
+   let k1 = 11 - ((3 * nrs[0] + 7 * nrs[1] + 6 * nrs[2] + 1 * nrs[3] + 8 * nrs[4] +
+      9 * nrs[5] + 4 * nrs[6] + 5 * nrs[7] + 2 * nrs[8]) % 11)
+   let k2 = 11 - ((5 * nrs[0] + 4 * nrs[1] + 3 * nrs[2] + 2 * nrs[3] + 7 *
+      nrs[4] + 6 * nrs[5] + 5 * nrs[6] + 4 * nrs[7] + 3 * nrs[8] + 2 * k1) % 11)
+
+   if (k1 === 11) k1 = 0
+   if (k2 === 11) k2 = 0
+
+   return k1 < 10 && k2 < 10 && k1 == nrs[9] && k2 == nrs[10] ?
+      [] : ["checksums don't match"]
+}
+
+// copied from https://stackoverflow.com/questions/5812220/how-to-validate-a-date
+const birthdate = (digits: string, type: string): Array<DATE_ERROR> => {
+   if (type === 'dnr') {
+      digits = (Number(digits.substring(0, 1)) - 4) + digits.substring(1)
+   } else if (type === 'hnr') {
+      digits = digits.substring(0, 2) + (Number(digits.substring(2, 3)) - 4) + digits.substring(3)
+   } else if (type === 'tnr') {
+      digits = digits.substring(0, 2) + (Number(digits.substring(2, 3)) - 8) + digits.substring(3)
+   } else if (type === 'dnr-and-hnr') {
+      digits = (Number(digits.substring(0, 1)) - 4) + digits.substring(1, 2) + (Number(digits.substring(2, 3)) - 4) + digits.substring(3)
+   }
+
+   const day = Number(digits.substring(0, 2))
+   const month = Number(digits.substring(2, 4))
+   const yearString = digits.substring(4, 6)
+   const year = yearString == '00' ? 2000 : Number(yearString)
+
+   // set year 00 default to 2000 instead of 1900
+   const date = new Date(year, month - 1, day)
+
+   return (date && (date.getMonth() + 1) == month && date.getDate() == day) ?
+      [] : ["invalid date"]
+ }
+

tests/fnr.spec.d.ts

@@ -0,0 +1 @@
+export {};