diff --git a/snippets/mask.md b/snippets/mask.md
new file mode 100644
index 000000000..c030d0828
--- /dev/null
+++ b/snippets/mask.md
@@ -0,0 +1,20 @@
+### mask
+
+Replaces all but the last `num` of characters with the specified mask character.
+
+Use `String.slice()` to grab the portion of the characters that need to be masked and use `String.replace()` with a regex to replace every character with the mask character. 
+Concatenate the masked characters with the remaining unmasked portion of the string.
+Omit the second argument, `num`, to keep a default of `4` characters unmasked.
+Omit the third argument, `mask`, to use a default character of `'*'` for the mask.
+
+```js
+const mask = (cc,num = 4,mask = '*') =>
+   ('' + cc).slice(0, -num).replace(/./g, mask) + ('' + cc).slice(-num);
+```
+
+```js
+mask(1234567890) // '******7890'
+mask(1234567890,3) // '*******890'
+mask(1234567890,4,'$') // '$$$$$$7890'
+mask(1234567890,-4,'$') // '1234$$$$$$'
+```