feat: support url option for evaluation

README.md

@@ -109,6 +109,8 @@ import { loadModule } from 'mlly'
 await loadModule('./hello.mjs', { from: import.meta.url })
 ```
 
+Options are same as for `evalModule`
+
 ### `evalModule`
 
 Evaluates JavaScript module code using dynamic imports with [`data:`](https://nodejs.org/api/esm.html#esm_data_imports) using `toDataURL`.
@@ -124,14 +126,22 @@ await evalModule(`
 `, { from: import.meta.url })
 ```
 
+**Options:**
+
+- [ resolve options ]
+- `url`: If provided, all `import.meta.url` usages within module will be rewritten. Also used as default `from` for relative import resolution
+
 ### `readModule`
 
-Resolves id using `resolve` and reads sourcecode.
+Resolve module path and read source contents. (currently only file protocol supported)
 
 ```js
-import { readModule } from 'mlly'
+import { resolve, readModule } from 'mlly'
 
-console.log(await readModule('./index.mjs', { from: import.meta.url }))
+const indexPath = await resolve('./index.mjs', { from: import.meta.url })
+
+// { code: '...", url: '...' }
+console.log(await readModule(indexPath))
 ```
 
 ### `toDataURL`
@@ -140,6 +150,8 @@ Convert code to [`data:`](https://nodejs.org/api/esm.html#esm_data_imports) URL
 
 All relative imports will be automatically resolved with `from` param using `resolveImports`.
 
+If `url` option is provided, all usages of `import.meta.url` will be rewritten too.
+
 ```js
 import { toDataURL } from 'mlly'
 

lib/index.d.ts

@@ -24,12 +24,14 @@ export function resolveImports (code: string, opts: ResolveOptions) : Promise<st
 
 // Evaluate
 
-export interface EvaluateOptions extends ResolveOptions {}
+export interface EvaluateOptions extends ResolveOptions {
+  url?: string
+}
+
 export function loadModule (id: string, opts?: EvaluateOptions) : Promise<any>
 export function evalModule (code: string, opts?: EvaluateOptions) : Promise<any>
-
-export function readModule (id: string, opts?: ResolveOptions) : Promise<any>
-export function toDataURL(code: string, opts?: ResolveOptions) : Promise<string>
+export function readModule (id: string, opts?: EvaluateOptions) : Promise<{ url: string, code: string}>
+export function toDataURL(code: string, opts?: EvaluateOptions) : Promise<string>
 
 // Utils
 

lib/index.mjs

@@ -70,22 +70,40 @@ export function createResolve (defaults) {
 const ESM_IMPORT_RE = /(?<=import .* from ['"])([^'"]+)(?=['"])|(?<=export .* from ['"])([^'"]+)(?=['"])|(?<=import\s*['"])([^'"]+)(?=['"])|(?<=import\s*\(['"])([^'"]+)(?=['"]\))/g
 
 export async function loadModule (id, opts = {}) {
-  const code = await readModule(id, opts)
-  return evalModule(code, opts)
+  const { url, code } = await readModule(id, opts)
+  return evalModule(code, {
+    url,
+    ...opts
+  })
 }
 
 export async function evalModule (code, opts = {}) {
   return import(await toDataURL(code, opts))
 }
 
 export async function readModule (id, opts) {
-  const resolved = await resolve(id, opts)
-  const code = await fsp.readFile(fileURLToPath(resolved), 'utf-8')
-  return code
+  const url = await resolve(id, opts)
+  const code = await fsp.readFile(fileURLToPath(url), 'utf-8')
+  return { url, code }
 }
 
 export async function toDataURL (code, opts) {
+  // Use url <> from as defaults of each other
+  if (!opts.url && opts.from) {
+    opts.url = opts.from
+  } else if (opts.url && !opts.from) {
+    opts.from = opts.url
+  }
+
+  // Resolve relative imports
   code = await resolveImports(code, opts)
+
+  // Rewrite import.meta.url
+  if (opts.url) {
+    code = code.replace(/import\.meta\.url/g, `'${opts.url}'`)
+  }
+
+  // Convert to base64
   const base64 = Buffer.from(code).toString('base64')
   return `data:text/javascript;base64,${base64}`
 }

test/hello.mjs

@@ -1 +1 @@
-console.log('Hello world!')
+console.log('Hello world from', import.meta.url)