iron-meta

iron-meta is a generic element you can use for sharing information across the DOM tree. It uses monostate pattern such that any instance of iron-meta has access to the shared information. You can use iron-meta to share whatever you want (or create an extension [like x-meta] for enhancements).

The iron-meta instances containing your actual data can be loaded in an import, or constructed in any way you see fit. The only requirement is that you create them before you try to access them.

Examples:

If I create an instance like this:

<iron-meta key="info" value="foo/bar"></iron-meta>

Note that value="foo/bar" is the metadata I've defined. I could define more attributes or use child nodes to define additional metadata.

Now I can access that element (and it's metadata) from any iron-meta instance via the byKey method, e.g.

meta.byKey('info').getAttribute('value');

Pure imperative form would be like:

document.createElement('iron-meta').byKey('info').getAttribute('value');

Or, in a Polymer element, you can include a meta in your template:

<iron-meta id="meta"></iron-meta>

this.$.meta.byKey('info').getAttribute('value');