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URL Parameters

URL parameters on the metapage URL are injected into metaframe URLs at runtime, using a _param_ substitution syntax. This turns a metapage into a parameterized, configurable view — effectively a function with URL arguments.

Substitution syntax​

Any URL search or hash parameter on the metapage URL is injected into metaframe URLs that contain _<param-name>_ as a placeholder:

Metapage URL:

https://metapage.io/m/<id>?version=v1.2.3

Metaframe URL in metapage.json:

https://github.com/myorg/myrepo/tree/_version_

Resolved metaframe URL at runtime:

https://github.com/myorg/myrepo/tree/v1.2.3

The metapage URL becomes a versioned, shareable handle to a specific state of the workflow.

Reading injected parameters in JavaScript​

Use @metapages/hash-query to read parameters from within a metaframe:

import { getHashParamFromWindow } from "https://cdn.jsdelivr.net/npm/@metapages/hash-query@latest/+esm";

const version = getHashParamFromWindow("version");
console.log(`version=${version}`);

Or with npm:

npm install @metapages/hash-query
import { getHashParamFromWindow } from "@metapages/hash-query";

Container metaframes​

All metapage URL parameters are available as environment variables inside the container. For example:

https://metapage.io/m/<id>?MODEL_NAME=llama3

Makes MODEL_NAME=llama3 available in the container environment.

This is particularly useful for pointing a container at a specific git commit or branch — see Git refs in URLs.

Example: version-pinned workflow​

https://metapage.io/m/<id>?git-ref=affeff5e706b446358f4b619058c6e93afe8836f

With this container URL in the metapage definition:

https://github.com/myorg/myrepo/tree/_git-ref_

The container is built from the exact commit specified in the URL parameter. Changing the URL changes the version without modifying the metapage definition.