feat(workers): add support for workers style environemnt. See precons…

…truct#431

packages/cli/src/build/config.ts

@@ -207,5 +207,40 @@ export function getRollupConfigs(pkg: Package, aliases: Aliases) {
     });
   }
 
+  let hasWorkerField = pkg.entrypoints[0].json.worker !== undefined;
+
+  if (hasWorkerField) {
+    configs.push({
+      config: getRollupConfig(
+        pkg,
+        pkg.entrypoints,
+        aliases,
+        "worker",
+        () => {}
+      ),
+      outputs: [
+        {
+          format: "cjs" as const,
+          entryFileNames: "[name].worker.cjs.js",
+          chunkFileNames: "dist/[name]-[hash].worker.cjs.js",
+          dir: pkg.directory,
+          exports: "named" as const,
+          interop,
+          plugins: cjsPlugins,
+        },
+        ...(hasModuleField
+          ? [
+              {
+                format: "es" as const,
+                entryFileNames: "[name].worker.esm.js",
+                chunkFileNames: "dist/[name]-[hash].worker.esm.js",
+                dir: pkg.directory,
+              },
+            ]
+          : []),
+      ],
+    });
+  }
+
   return configs;
 }

packages/cli/src/build/rollup.ts

@@ -31,7 +31,12 @@ const makeExternalPredicate = (externalArr: string[]) => {
   return (id: string) => pattern.test(id);
 };
 
-export type RollupConfigType = "umd" | "browser" | "node-dev" | "node-prod";
+export type RollupConfigType =
+  | "umd"
+  | "browser"
+  | "node-dev"
+  | "node-prod"
+  | "worker";
 
 export let getRollupConfig = (
   pkg: Package,
@@ -193,6 +198,15 @@ export let getRollupConfig = (
           },
           preventAssignment: true,
         }),
+      type === "worker" &&
+        replace({
+          values: {
+            ["typeof " + "document"]: JSON.stringify("undefined"),
+            ["typeof " + "window"]: JSON.stringify("undefined"),
+            ["typeof " + "process"]: JSON.stringify("undefined"),
+          },
+          preventAssignment: true,
+        }),
     ].filter((x): x is Plugin => !!x),
   };
 

packages/cli/src/dev.ts

@@ -218,6 +218,17 @@ unregister();
               );
             }
           }
+          if (entrypoint.json.worker) {
+            let workerField = validFields.worker(entrypoint);
+            for (let key of Object.keys(workerField)) {
+              promises.push(
+                fs.symlink(
+                  entrypoint.source,
+                  path.join(entrypoint.directory, workerField[key])
+                )
+              );
+            }
+          }
 
           return Promise.all(promises);
         })

packages/cli/src/entrypoint.ts

@@ -9,6 +9,7 @@ export class Entrypoint extends Item<{
   module?: JSONValue;
   "umd:main"?: JSONValue;
   browser?: JSONValue;
+  worker?: JSONValue;
   preconstruct: {
     source?: JSONValue;
     umdName?: JSONValue;

packages/cli/src/init.ts

@@ -93,6 +93,30 @@ async function doInit(pkg: Package) {
     }
   }
 
+  let someEntrypointsHaveAWorkerField = pkg.entrypoints.some(
+    (entrypoint) => entrypoint.json.worker !== undefined
+  );
+
+  let someEntrypointsHaveAnInvalidWorkerField = pkg.entrypoints.some(
+    (entrypoint) => !isFieldValid.worker(entrypoint)
+  );
+  if (
+    someEntrypointsHaveAWorkerField &&
+    someEntrypointsHaveAnInvalidWorkerField
+  ) {
+    let shouldFixWorkerField = await confirms.fixWorkerField(pkg);
+    if (shouldFixWorkerField) {
+      pkg.setFieldOnEntrypoints("worker");
+    } else {
+      throw new FixableError(
+        errors.fieldMustExistInAllEntrypointsIfExistsDeclinedFixDuringInit(
+          "worker"
+        ),
+        pkg.name
+      );
+    }
+  }
+
   await Promise.all(pkg.entrypoints.map((x) => x.save()));
 }
 

packages/cli/src/messages.ts

@@ -2,7 +2,7 @@ import { PKG_JSON_CONFIG_FIELD } from "./constants";
 import { createPromptConfirmLoader } from "./prompt";
 import chalk from "chalk";
 
-type Field = "main" | "module" | "browser" | "umd:main";
+type Field = "main" | "module" | "browser" | "umd:main" | "worker";
 
 export let errors = {
   noSource: (source: string) =>
@@ -38,6 +38,9 @@ export let confirms = {
   fixBrowserField: createPromptConfirmLoader(
     "would you like to fix the browser build?"
   ),
+  fixWorkerField: createPromptConfirmLoader(
+    "would you like to fix the worker build?"
+  ),
   createEntrypointPkgJson: createPromptConfirmLoader(
     "A package.json file does not exist for this entrypoint, would you like to create one automatically?"
   ),

packages/cli/src/package.ts

@@ -26,7 +26,7 @@ function getFieldsUsedInEntrypoints(
   for (let descriptor of descriptors) {
     if (descriptor.contents !== undefined) {
       let parsed = jsonParse(descriptor.contents, descriptor.filename);
-      for (let field of ["module", "umd:main", "browser"] as const) {
+      for (let field of ["module", "umd:main", "browser", "worker"] as const) {
         if (parsed[field] !== undefined) {
           fields.add(field);
         }
@@ -47,7 +47,7 @@ function getPlainEntrypointContent(
     string | Record<string, string>
   >> = {};
   for (const field of fields) {
-    if (field === "browser") {
+    if (field === "browser" || field === "worker") {
       obj[field] = validFieldsFromPkg[field](
         pkg,
         fields.has("module"),
@@ -264,7 +264,9 @@ export class Package extends Item<{
     return pkg;
   }
 
-  setFieldOnEntrypoints(field: "main" | "browser" | "module" | "umd:main") {
+  setFieldOnEntrypoints(
+    field: "main" | "browser" | "module" | "umd:main" | "worker"
+  ) {
     this.entrypoints.forEach((entrypoint) => {
       entrypoint.json = setFieldInOrder(
         entrypoint.json,

packages/cli/src/utils.ts

@@ -15,11 +15,12 @@ let fields = [
   "module",
   "umd:main",
   "browser",
+  "worker",
 ];
 
 export function setFieldInOrder<
   Obj extends { [key: string]: any },
-  Key extends "main" | "module" | "umd:main" | "browser",
+  Key extends "main" | "module" | "umd:main" | "browser" | "worker",
   Val extends any
 >(obj: Obj, field: Key, value: Val): Obj & { [k in Key]: Val } {
   if (field in obj) {
@@ -129,6 +130,22 @@ export const validFieldsFromPkg = {
     }
     return obj;
   },
+  worker(
+    pkg: Package,
+    hasModuleBuild: boolean,
+    entrypointName: string,
+    forceStrategy?: DistFilenameStrategy
+  ) {
+    let safeName = getDistName(pkg, entrypointName, forceStrategy);
+
+    let obj = {
+      [`./dist/${safeName}.cjs.js`]: `./dist/${safeName}.worker.cjs.js`,
+    };
+    if (hasModuleBuild) {
+      obj[`./dist/${safeName}.esm.js`] = `./dist/${safeName}.worker.esm.js`;
+    }
+    return obj;
+  },
 };
 
 export const validFields = {
@@ -148,6 +165,14 @@ export const validFields = {
       entrypoint.name
     );
   },
+  worker(entrypoint: Entrypoint, forceStrategy?: DistFilenameStrategy) {
+    return validFieldsFromPkg.worker(
+      entrypoint.package,
+      entrypoint.json.module !== undefined,
+      entrypoint.name,
+      forceStrategy
+    );
+  },
 };
 
 export function flowTemplate(hasDefaultExport: boolean, relativePath: string) {

packages/cli/src/validate-package.ts

@@ -15,6 +15,7 @@ export async function fixPackage(pkg: Package) {
     module: pkg.entrypoints.some((x) => x.json.module !== undefined),
     "umd:main": pkg.entrypoints.some((x) => x.json["umd:main"] !== undefined),
     browser: pkg.entrypoints.some((x) => x.json.browser !== undefined),
+    worker: pkg.entrypoints.some((x) => x.json.worker !== undefined),
   };
 
   keys(fields)
@@ -41,6 +42,7 @@ export function validatePackage(pkg: Package) {
     module: pkg.entrypoints[0].json.module !== undefined,
     "umd:main": pkg.entrypoints[0].json["umd:main"] !== undefined,
     browser: pkg.entrypoints[0].json.browser !== undefined,
+    worker: pkg.entrypoints[0].json.worker !== undefined,
   };
 
   pkg.entrypoints.forEach((entrypoint) => {

packages/cli/src/validate.ts

@@ -25,6 +25,9 @@ export const isFieldValid = {
   browser(entrypoint: Entrypoint): boolean {
     return equal(entrypoint.json.browser, validFields.browser(entrypoint));
   },
+  worker(entrypoint: Entrypoint): boolean {
+    return equal(entrypoint.json.worker, validFields.worker(entrypoint));
+  },
 };
 
 export function isUmdNameSpecified(entrypoint: Entrypoint) {
@@ -38,7 +41,13 @@ function validateEntrypoint(entrypoint: Entrypoint, log: boolean) {
     logger.info(infos.validEntrypoint, entrypoint.name);
   }
   const fatalErrors: FatalError[] = [];
-  for (const field of ["main", "module", "umd:main", "browser"] as const) {
+  for (const field of [
+    "main",
+    "module",
+    "umd:main",
+    "browser",
+    "worker",
+  ] as const) {
     if (field !== "main" && entrypoint.json[field] === undefined) {
       continue;
     }

site/src/pages/configuration.mdx

@@ -183,3 +183,9 @@ Example:
 The `browser` field specifies alias files exclusive to browsers. This allows you to create different bundles from your source code based on `typeof window` and `typeof document` checks - thanks to that you can, for example, remove server-only code (just for those bundles).
 
 **Note:** Those files are not meant to be consumed by browsers "as is". They just assume browser-like environment, but they still can contain for example references to `process.env.NODE_ENV` as that is meant to be replaced by a consuming bundler.
+
+### `worker`
+
+The `worker` field specifies alias files exclusive to DOM-less javascript environments like CloudFlare Workers. This allows you to create different bundles from your source code based on `typeof window` and `typeof document` and `typeof process` checks - thanks to that you can, for example, remove broser-only or Node.js-only code (just for those bundles).
+
+**Note:** Those files are not meant to be consumed by workers "as is". They just assume worker-like environment, but they still can contain for example references to `process.env.NODE_ENV` as that is meant to be replaced by a consuming bundler.