Add a Map Local rule#

Map Local serves matching URLs from a directory on disk instead of fetching them from the network. Use it when you want to swap in a modified JavaScript bundle, mock an API response from a JSON file, or serve a fixture directory as if it were an origin.

Add a Map Local rule#

1. Open the Map Local sub-tab.
2. Select + Add new rule at the bottom of the list. A new empty row appears.
3. Fill in the fields described below.

What each field controls#

• URL Pattern: the request URL pattern to match. The dropdown to its left controls how the pattern is interpreted: Contains, Starts with, or Regex.
• Local Dir: the directory on disk to serve files from. Paths can be absolute or relative to your home directory.
• Strip Prefix: a leading path segment to strip before looking up the file. For example, with Strip Prefix set to /api/v1, a request for /api/v1/users looks up users inside Local Dir. This field is optional.
• Fallback: a filename (typically index.html) to serve when the request does not map to a specific file. Use this for single-page application routing, where the server returns the SPA shell for any route. This field is optional.

How a request resolves#

When a request matches the URL pattern:

1. The request URL has the Strip Prefix removed from the start of its path, if set.
2. GraphDagger looks for that path inside Local Dir.
3. If the file exists, GraphDagger serves it. If not, GraphDagger looks for Fallback and serves that instead.
4. If neither exists, the request fails with a 404.

Switch a local mapping on or off#

The toggle on the left of the row controls whether the rule is active. Turn it off to keep the rule without a file served from disk.

Test the mapping first#

To check a rule against a sample URL without firing a real request, see Testing a Map Local.