[](https://www.npmjs.com/package/@polymer/iron-demo-helpers) [](https://travis-ci.org/PolymerElements/iron-demo-helpers) [](https://webcomponents.org/element/@polymer/iron-demo-helpers) ## <demo-snippet> `demo-snippet` is a helper element that displays the source of a code snippet and its rendered demo. It can be used for both native elements and Polymer elements. See: [Documentation](https://www.webcomponents.org/element/@polymer/iron-demo-helpers), [Demo](https://www.webcomponents.org/element/@polymer/iron-demo-helpers/demo/demo/index.html). ## Usage ### Installation ``` npm install --save @polymer/iron-demo-helpers ``` ### In an html file ```html ``` ### In a Polymer 3 element ```js import {PolymerElement, html} from '@polymer/polymer'; import '@polymer/iron-demo-helpers/demo-snippet.js'; import '@polymer/paper-checkbox/paper-checkbox.js'; class SampleElement extends PolymerElement { static get template() { return html` `; } } customElements.define('sample-element', SampleElement); ``` ## <url-bar> `url-bar` is a helper element that displays a simple read-only URL bar if and only if the page is in an iframe. In this way we can demo elements that deal with the URL in our iframe-based demo environments. If the page is not in an iframe, the url-bar element is not displayed. ## Contributing If you want to send a PR to this element, here are the instructions for running the tests and demo locally: ### Installation ```sh git clone https://github.com/PolymerElements/iron-demo-helpers cd iron-demo-helpers npm install npm install -g polymer-cli ``` ### Running the demo locally ```sh polymer serve --npm open http://127.0.0.1:/demo/ ``` ### Running the tests ```sh polymer test --npm ``` ## Known Issues If you add a `script type="module"` inside a `demo-snippet`, the demo will not be functional on non-module browsers (like IE11). If you need to use a `script type="module"` and want to display its code in the `demo-snippet`, a possible workaround is to duplicate the contents of the script outside of the `demo-snippet` -- that way `polymer serve` (or whatever solution you're using to ES5-ify the code) will convert the main document `module` to UMD, but will leave the displayed code untouched. Here is an example: ```html ```