maximkott · April 15, 2024 20:43 · Jan 10, 2023 · Aug 5, 2020 · Mar 21, 2017
diff --git a/mask.js b/mask.js
@@ -100,7 +100,7 @@ export const maskString = (
 };
 
 // now you can do
-maskString('+410767007070', '+YXX? YX XXX XX XX', { X: /0-9/, Y: /[1-9]/ })
-// or
-maskString('+3800767007070', '+YXX? YX XXX XX XX', { X: /0-9/, Y: /[1-9]/ })
-// returns +380 76 700 70 70
+console.log(maskString("+41 767007070", "+YXX? YX XXX XX XX", { X: /[0-9]/, Y: /[1-9]/ }))
+// +41 76 700 70 70
+console.log(maskString("+3800767007070", "+YXX? YX XXX XX XX", { X: /[0-9]/, Y: /[1-9]/ }))
+// +380 76 700 70 70
diff --git a/mask.js b/mask.js
@@ -1,42 +1,52 @@
-function maskString(value, mask, maskPatterns) {
-  value = value || ''
+export const maskString = (
+  value: any,
+  mask: string,
+  maskPatterns: Record<string, RegExp | ((char: string) => boolean)>
+) => {
+  value = value || '';
   mask = mask || '';
   maskPatterns = maskPatterns || {};
 
-  var maskedValue = '';
+  let maskedValue = '';
   // array representation of string under test
-  var valueParts = value.split('');
+  const valueParts = value.split('');
   // array representation of the mask
-  var maskParts = mask.split('');
+  const maskParts = mask.split('');
 
   // as long as there are still characters left in
   // the original string, one must try to mask them
   while (valueParts.length > 0) {
     // take the first character and remove
     // it from the original string
-    var unmaskedChar = valueParts.shift()
+    let unmaskedChar = valueParts.shift();
 
     // as long as the character has not been masked
     // one must try to find a mask
     while (unmaskedChar !== null) {
       // take the first mask character from
       // the mask string
-      var maskChar = maskParts.shift();
+      const maskChar = maskParts.shift();
+      const maskCharIsOptional = maskParts[0] === '?';
+
+      // remove '?' from the mask parts
+      if (maskCharIsOptional) {
+        maskParts.shift();
+      }
 
       // make sure the masking character exists
       // otherwise this means that the original string
       // exceeds the masking pattern length
       if (maskChar !== undefined) {
         // try to find a pattern for the particular
         // mask character
-        var maskPattern = maskPatterns[maskChar.toUpperCase()];
+        const maskPattern = maskPatterns[maskChar.toUpperCase()];
 
         // if there is no pattern configured for
         // this particular mask character, assume
         // the mask character is a placeholder / formatting
         // value that must be added to the string
         if (maskPattern !== undefined) {
-          var check = false;
+          let check = false;
 
           // mask pattern can be either a function
           if (typeof maskPattern === 'function') {
@@ -51,20 +61,28 @@ function maskString(value, mask, maskPatterns) {
           // it can bee added to the final masked value
           if (check) {
             maskedValue += unmaskedChar;
+            unmaskedChar = null;
+          }
+          // the character did not pass the mask check,
+          // however, the mask was optional, we can skip it
+          else if (!check && maskCharIsOptional) {
           }
           // otherwise one must put the pattern back into
           // the array so the next character can try to
           // pass the mask check
           else {
             maskParts.unshift(maskChar);
+            unmaskedChar = null;
           }
-
-          unmaskedChar = null;
         }
         // mask character is a placeholder / formatting value
         // and must be added to the masked string
         else {
           maskedValue += maskChar;
+
+          if (unmaskedChar === maskChar) {
+            unmaskedChar = null;
+          }
         }
       }
       // no masking character could be found,
@@ -79,8 +97,10 @@ function maskString(value, mask, maskPatterns) {
   }
 
   return maskedValue;
-}
+};
 
 // now you can do
-maskString('+410767007070', '+XX SX XXX XX XX', {X: /\d/, S: /[1-9]/});
-// returns +41 76 700 70 70
+maskString('+410767007070', '+YXX? YX XXX XX XX', { X: /0-9/, Y: /[1-9]/ })
+// or
+maskString('+3800767007070', '+YXX? YX XXX XX XX', { X: /0-9/, Y: /[1-9]/ })
+// returns +380 76 700 70 70
diff --git a/mask.js b/mask.js
@@ -0,0 +1,86 @@
+function maskString(value, mask, maskPatterns) {
+  value = value || ''
+  mask = mask || '';
+  maskPatterns = maskPatterns || {};
+
+  var maskedValue = '';
+  // array representation of string under test
+  var valueParts = value.split('');
+  // array representation of the mask
+  var maskParts = mask.split('');
+
+  // as long as there are still characters left in
+  // the original string, one must try to mask them
+  while (valueParts.length > 0) {
+    // take the first character and remove
+    // it from the original string
+    var unmaskedChar = valueParts.shift()
+
+    // as long as the character has not been masked
+    // one must try to find a mask
+    while (unmaskedChar !== null) {
+      // take the first mask character from
+      // the mask string
+      var maskChar = maskParts.shift();
+
+      // make sure the masking character exists
+      // otherwise this means that the original string
+      // exceeds the masking pattern length
+      if (maskChar !== undefined) {
+        // try to find a pattern for the particular
+        // mask character
+        var maskPattern = maskPatterns[maskChar.toUpperCase()];
+
+        // if there is no pattern configured for
+        // this particular mask character, assume
+        // the mask character is a placeholder / formatting
+        // value that must be added to the string
+        if (maskPattern !== undefined) {
+          var check = false;
+
+          // mask pattern can be either a function
+          if (typeof maskPattern === 'function') {
+            check = maskPattern(unmaskedChar);
+          }
+          // or a regex string
+          else if (maskPattern instanceof RegExp) {
+            check = maskPattern.test(unmaskedChar);
+          }
+
+          // if character has passed the mask check,
+          // it can bee added to the final masked value
+          if (check) {
+            maskedValue += unmaskedChar;
+          }
+          // otherwise one must put the pattern back into
+          // the array so the next character can try to
+          // pass the mask check
+          else {
+            maskParts.unshift(maskChar);
+          }
+
+          unmaskedChar = null;
+        }
+        // mask character is a placeholder / formatting value
+        // and must be added to the masked string
+        else {
+          maskedValue += maskChar;
+        }
+      }
+      // no masking character could be found,
+      // the original string is probably longer
+      // then the mask pattern and therefore
+      // the leftovers can be cut off
+      else {
+        // reset current character to continue the loop
+        unmaskedChar = null;
+      }
+    }
+  }
+
+  return maskedValue;
+}
+
+// now you can do
+maskString('+410767007070', '+XX SX XXX XX XX', {X: /\d/, S: /[1-9]/});
+// returns +41 76 700 70 70