Add babel-plugin-unpkg-rewrite package

packages/babel-plugin-unpkg-rewrite/README.md

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+A [Babel](http://babeljs.io/) plugin that rewrites bare ES module specifiers as
+[unpkg](https://unpkg.com) URLs.
+
+## input
+
+```jsx
+import React from "react"
+import router from "@angular/router"
+import map from "lodash.map"
+import fs from "pn/fs"
+import cupcakes from "./cupcakes"
+import shoelaces from "/shoelaces"
+import something from "//something.com/whatevs"
+import something from "http://something.com/whatevs"
+let ReactDOM = require("react-dom")
+export React from "react"
+export { Component } from "react"
+export * from "react"
+export var message = "hello"
+```
+
+## output
+
+```jsx
+import React from "https://unpkg.com/react@15.6.1?module"
+import router from "https://unpkg.com/@angular/router@4.3.5?module"
+import map from "https://unpkg.com/lodash.map@4.6.0?module"
+import fs from "https://unpkg.com/pn@1.0.0/fs?module"
+import cupcakes from "./cupcakes?module"
+import shoelaces from "/shoelaces?module"
+import something from "//something.com/whatevs"
+import something from "http://something.com/whatevs"
+let ReactDOM = require("react-dom")
+export React from "https://unpkg.com/react@15.6.1?module"
+export { Component } from "https://unpkg.com/react@15.6.1?module"
+export * from "https://unpkg.com/react@15.6.1?module"
+export var message = "hello"
+```

packages/babel-plugin-unpkg-rewrite/modules/__tests__/index-test.js

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+const babel = require("babel-core")
+const unpkgRewrite = require("../index")
+
+const testCases = [
+  {
+    before: "import React from 'react';",
+    after: "import React from 'https://unpkg.com/react@15.6.1?module';"
+  },
+  {
+    before: "import router from '@angular/router';",
+    after: "import router from 'https://unpkg.com/@angular/router@4.3.5?module';"
+  },
+  {
+    before: "import map from 'lodash.map';",
+    after: "import map from 'https://unpkg.com/lodash.map@4.6.0?module';"
+  },
+  {
+    before: "import fs from 'pn/fs';",
+    after: "import fs from 'https://unpkg.com/pn@1.0.0/fs?module';"
+  },
+  {
+    before: "import cupcakes from './cupcakes';",
+    after: "import cupcakes from './cupcakes?module';"
+  },
+  {
+    before: "import shoelaces from '/shoelaces';",
+    after: "import shoelaces from '/shoelaces?module';"
+  },
+  {
+    before: "import something from '//something.com/whatevs';",
+    after: "import something from '//something.com/whatevs';"
+  },
+  {
+    before: "import something from 'http://something.com/whatevs';",
+    after: "import something from 'http://something.com/whatevs';"
+  },
+  {
+    before: "let ReactDOM = require('react-dom');",
+    after: "let ReactDOM = require('react-dom');"
+  },
+  {
+    before: "export React from 'react';",
+    after: "export React from 'https://unpkg.com/react@15.6.1?module';"
+  },
+  {
+    before: "export { Component } from 'react';",
+    after: "export { Component } from 'https://unpkg.com/react@15.6.1?module';"
+  },
+  {
+    before: "export * from 'react';",
+    after: "export * from 'https://unpkg.com/react@15.6.1?module';"
+  },
+  {
+    before: "export var message = 'hello';",
+    after: "export var message = 'hello';"
+  }
+]
+
+const dependencies = {
+  react: "15.6.1",
+  "@angular/router": "4.3.5",
+  "lodash.map": "4.6.0",
+  pn: "1.0.0"
+}
+
+testCases.forEach(testCase => {
+  describe(`rewriting "${testCase.before}"`, () => {
+    it(`becomes "${testCase.after}"`, () => {
+      const result = babel.transform(testCase.before, {
+        plugins: [unpkgRewrite(dependencies)]
+      })
+
+      expect(result.code).toEqual(testCase.after)
+    })
+  })
+})

packages/babel-plugin-unpkg-rewrite/modules/index.js

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+const unpkg = require("unpkg")
+const warning = require("warning")
+
+function unpkgRewrite(dependencies = {}) {
+  return {
+    inherits: require("babel-plugin-syntax-export-extensions"),
+
+    visitor: {
+      "ImportDeclaration|ExportNamedDeclaration|ExportAllDeclaration"(path) {
+        if (!path.node.source) return // probably a variable declaration
+
+        const id = path.node.source.value
+
+        if (unpkg.isRemoteModuleIdentifier(id)) {
+          return // leave it alone
+        } else if (unpkg.isLocalModuleIdentifier(id)) {
+          path.node.source.value = `${id}?module`
+        } else if (unpkg.isBareModuleIdentifier(id)) {
+          const { packageName, file } = unpkg.parseBareModuleIdentifier(id)
+
+          warning(
+            dependencies[packageName],
+            'Missing version info for package "%s" in dependencies; falling back to "latest"',
+            packageName
+          )
+
+          const version = dependencies[packageName] || "latest"
+
+          path.node.source.value = `https://unpkg.com/${packageName}@${version}${file}?module`
+        }
+      }
+    }
+  }
+}
+
+module.exports = unpkgRewrite

packages/babel-plugin-unpkg-rewrite/package.json

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+{
+  "name": "babel-plugin-unpkg-rewrite",
+  "version": "3.3.0",
+  "description": "Rewrite bare ES module specifiers as unpkg.com URLs with Babel",
+  "repository": "unpkg/unpkg",
+  "license": "MIT",
+  "files": [
+    "modules/*.js"
+  ],
+  "main": "modules/index.js",
+  "dependencies": {
+    "babel-plugin-syntax-export-extensions": "^6.13.0",
+    "unpkg": "^0.2.0",
+    "warning": "^3.0.0"
+  },
+  "devDependencies": {
+    "babel": "^6.23.0",
+    "babel-cli": "^6.22.2",
+    "babel-core": "^6.23.1"
+  },
+  "keywords": [
+    "babel",
+    "babel-plugin",
+    "resolve",
+    "module",
+    "modules",
+    "esm",
+    "unpkg"
+  ]
+}