henhan · April 13, 2016 13:52 · Apr 13, 2016
diff --git a/swedishIdUtils.js b/swedishIdUtils.js
@@ -0,0 +1,72 @@
+'use strict';
+
+function isValid(id) {
+    // Make sure we have a string
+    id = '' + id;
+    if (id.match(/^[\-\s+\d]+$/) === null) {
+        return false;
+    }
+    // Remove all non digits
+    id = id.replace(/\D/g, '')
+    if (id.length !== 10 && id.length !== 12) {
+        return false;
+    }
+    if (id.length === 12) {
+        // Validate century prefix and reduce string that is to be validated to 10 digits
+        // Other prefixes than these indicate that it is a company
+        var prefix = parseInt(id.substring(0, 2));
+        if (prefix < 18 || prefix > 20) {
+            return false;
+        }
+        // Validate that year is not greater than current
+        var currentYear = (new Date()).getFullYear();
+        if (parseInt(id.substring(0, 4)) > currentYear) {
+            return false;
+        }
+        id = id.substring(2);
+    }
+    var sum = 0;
+    for (var i = 0; i < id.length; i++) {
+        var value = parseInt(id.charAt(i));
+        sum += getValidationValue(i, value);
+    }
+    return sum % 10 == 0;
+}
+
+function getValidationValue(index, baseValue) {
+    if (index % 2 !== 0) {
+        return baseValue;
+    }
+    var doubled = 2 * baseValue;
+    if (doubled < 10) {
+        return doubled;
+    } else {
+        return 1 + (doubled - 10);
+    }
+}
+
+var toTest = [
+    8209244113,
+    "8209244113",
+    "820924-4113",
+    "820924+4113",
+    "18820924-4113",
+    "19820924-4113",
+    "201302091077",
+    " 82 09 24 - 4113",
+    null,
+    "",
+    "8209244119",
+    "AA09244113",
+    "AA8209244113",
+    "820924B4113",
+    "17820924-4113",
+    "20820924-4113",
+    "201202091077",
+    " 82 09 24 _ 4014"
+];
+
+toTest.forEach(function(value) {
+    var ok = isValid(value);
+    console.log(value + " is valid: " + (ok ? 'true' : 'false'));
+})