DYAL

JS / CSS asset loader to enable retry and fallback use cases

Use cases

• If the CDN fails, download an asset from the original domain
• If SRI validation fails, fall back to a different resource
• If an asset fails to load, retry

Design goals

• Compact: halfway small so to be directly included in each page: it’s 1.6K right now and it’s likely gonna shrink. This is why it does not have (and should not have) any external runtime dependencies
• Familiar: Sane defaults to not offer too many surprises
• Recognizable: offers a Promise based API for asynchronicity

Full disclosure: DYAL is mostly an excuse for me to learn some TypeScript but maybe it’s also useful.

Tooling

• yarn install will the relevant development dependencies
• yarn build will output dist/loader.js which is meant to be used
• yarn testbed will build a development version and run a webserver on localhost:8081 to serve a testbed (open the developer console to see if things work)
• yarn fmt will format all the code
• yarn dev will run rollup in watch mode