diff --git a/aio/content/guide/service-worker-config.md b/aio/content/guide/service-worker-config.md
index 4b4ce13555a..a33b182c353 100644
--- a/aio/content/guide/service-worker-config.md
+++ b/aio/content/guide/service-worker-config.md
@@ -21,7 +21,7 @@ All file paths must begin with `/`, which corresponds to the deployment director
-Unless otherwise commented, patterns use a limited glob format:
+Unless otherwise commented, patterns use a **limited*** glob format that internally will be converted into regex:
| Glob formats | Details |
|:--- |:--- |
@@ -30,6 +30,32 @@ Unless otherwise commented, patterns use a limited glob format:
| `?` | Matches exactly one character excluding `/` |
| `!` prefix | Marks the pattern as being negative, meaning that only files that don't match the pattern are included |
+
+
+ **\*** Pay attention that some characters with a special meaning in a regular expression are not escaped and also the pattern is not wrapped in `^`/`$` in the internal glob to regex conversion.
+
+ * `$` is a special character in regex that matches the end of the string and will not be automatically escaped when converting the glob pattern to a regular expression.
+ If you want to literally match the `$` character, you have to escape it yourself (with `\\$`).
+
+
+
+ For example, the glob pattern `/foo/bar/$value` results in an unmatchable expression, because it is impossible to have a string that has any characters after it has ended.
+
+
+
+ * The pattern will not be automatically wrapped in `^` and `$` when converting it to a regular expression.
+ Therefore, the patterns will partially match the request URLs.
+ If you want your patterns to match the beginning and/or end of URLs, you can add `^`/`$` yourself.
+
+
+
+ For example, the glob pattern `/foo/bar/*.js` will match both `.js` and `.json` files.
+ If you want to only match `.js` files, use `/foo/bar/*.js$`.
+
+
+
+
+
Example patterns:
| Patterns | Details |