plugin transforms the imports/requires

experimental/babel-preset-env/src/transformPolyfillRequirePlugin.js

@@ -1,30 +1,30 @@
 // Should throw if no babel-polyfill import is found in all files
 // or if more than one is found
 
-// const builtIns = require('../data/builtIns.json');
-const builtIns = {
-  "typed/int8-array": {
-    "chrome": 5,
-    "opera": 12,
-    "firefox": 4,
-    "safari": 5,
-    "node": 0.12,
-    "ie": 10,
-    "android": 4,
-    "ios": 6
-  }
-};
-
 const polyfillSource = "babel-polyfill";
 let numPolyfillImports = 0;
 
 export default function ({ types: t }) {
   function checkNumPolyfillImports() {
     numPolyfillImports++;
-    if (numPolyfillImports > 1) {
-      console.log("multiple babel-polyfill imports found");
-      //throw new Error("multiple babel-polyfill imports found");
-    }
+    return numPolyfillImports > 1;
+  }
+
+  function addImport(polyfill) {
+    let declar = t.importDeclaration([], t.stringLiteral(`core-js/fn/${polyfill}`));
+    declar._blockHoist = 3;
+    return declar;
+  }
+
+  function addRequire(polyfill) {
+    return t.expressionStatement(
+      t.callExpression(
+        t.identifier("require"),
+        [
+          t.stringLiteral(`core-js/modules/${polyfill}`)
+        ]
+      )
+    );
   }
 
   function isRequire(path, source) {
@@ -41,19 +41,33 @@ export default function ({ types: t }) {
     ImportDeclaration(path, state) {
       if (path.node.specifiers.length === 0 &&
           path.node.source.value === polyfillSource) {
-        checkNumPolyfillImports();
+        if (checkNumPolyfillImports()) {
+          path.remove();
+          return;
+        }
 
-        // change
-        // path.node.source.value = "changed";
+        let imports = state.opts.polyfills.map((p) => addImport(p));
+        path.replaceWithMultiple(imports);
       }
     },
     Program(path, state) {
+      if (!state.opts.polyfills) {
+        throw path.buildCodeFrameError(`
+"polyfills" option not correctly passed
+to the transform-polyfill-require plugin
+in babel-preset-env
+`);
+      }
       path.get("body").forEach((bodyPath) => {
         if (isRequire(bodyPath, polyfillSource)) {
-          checkNumPolyfillImports();
+          if (checkNumPolyfillImports()) {
+            path.remove();
+            return;
+          }
 
-          // change
-          // bodyPath.node.expression.arguments[0].value = "changed";
+
+          let requires = state.opts.polyfills.map((p) => addRequire(p));
+          bodyPath.replaceWithMultiple(requires);
         }
       });
     }