The v1 API and migrating from 1.x

The v1 API

These keep the same signatures as 1.x:

• mport(spec, importOptions?): the default export
• MPort(options | ...origins)
• MPortURL(options | ...origins)
• options: { cdns, useCache: "localhost", cacheKey }
• @johnhenry/mport/firefox

Specifiers are "name@version[/path]" or { name, version, path }. With no path, mport reads the package’s package.json and imports its ESM entry.

@johnhenry/mport/firefox exists because older Firefox versions reject any two-argument import() at parse time. That entry point never uses the syntax. It reads package.json with fetch, so path-less specifiers work there too, and it ignores per-call import options.

Migrating from 1.x

Nothing you call has been removed. Change the install to @johnhenry/mport (the unscoped mport stays at 1.0.0). Behaviour changes, all of them bug fixes:

• The race waits for the first success. 1.x used Promise.race, so one CDN that failed quickly rejected the whole import.
• Scoped names parse correctly. "@scope/[email protected]/x.js" now works in string form.
• Origin arguments are honoured. MPort("a.cdn/", "b.cdn/"), as the old README showed, now uses those origins. 1.x silently ignored them.
• useCache: "localhost" works. It compared a URL host to an origin path and never matched.
• mport/firefox works. It referenced undefined variables. It is now @johnhenry/mport/firefox.
• Path-less imports prefer ESM. They pick the entry from exports → module → main; 1.x used main only. This can change which file loads for packages whose main is CommonJS.
• MPortURL returns a third element (debug info). [module, url] destructuring is unaffected.
• The npm package ships every file. The 1.0.0 tarball was missing config.mjs and race-which.mjs.

The default race still mixes builds (raw jsDelivr/unpkg files against jspm’s transformed output), because that is what 1.x did. For consistent builds, move to a router such as createRouter({ "*": race(jsDelivr(), unpkg()) }).