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You can configure sandboxes and templates with configuration files.

Configuration Files

There are some advanced use cases where you might need more control over a sandbox or template. That's why we support configuration files. Every template on CodeSandbox has a list of configuration files it supports. You can see the supported files under Configuration Files from the left-hand activity bar in the editor.

Configurations File UI

Configuration UI

Some configuration files can be configured using a UI. This UI will generate a configuration file based on its state.

Configurations File UI

Sandbox Configuration

A sandbox can be configured too, you can do this with sandbox.config.json. We support these options:

Option Description Possible Values Default Value
infiniteLoopProtection Whether we should throw an error if we detect an infinite loop true/false true
hardReloadOnChange Whether we should refresh the sandbox page on every change, good for sandboxes with global state true/false false
template Which sandbox template to use see here smart detection, w/ fallback to create-react-app
view Which view to show first in the preview Client: browser/console/problems/tests
Container: browser/console/problems/terminal
container The container object contains the configurable port and/or startScript option, for example: container: { port: 3212, startScript: "custom"}
port The main port which the browser window listens to 1024 - 65535 First opened port inside the container.
startScript Explicitly specify the start script used in a container sandbox, overriding the default value A String matching a script name defined under scripts in package.json dev / develop / serve / start