No core-js in core

babel.config.js

@@ -0,0 +1,22 @@
+const BABEL_ENV = process.env.BABEL_ENV;
+const IS_TEST = BABEL_ENV === "test"
+const ignore = IS_TEST ? [] : ['test/**/*.js']
+const targets = IS_TEST ? { node: "current" } : { browsers: "defaults" }
+
+module.exports = {
+  presets: [
+    [
+      "@babel/preset-env",
+      {
+        modules: ["cjs", "test"].includes(BABEL_ENV) ? "commonjs" : false,
+        targets
+      },
+    ],
+    "@babel/preset-react"
+  ],
+  plugins: [
+    "@babel/plugin-proposal-class-properties",
+    "@babel/plugin-proposal-optional-chaining"
+  ],
+  ignore,
+};

docs/3.x upgrade guide.md

@@ -0,0 +1,17 @@
+# 3.x Upgrade Guide
+
+## BREAKING
+
+### Bring your own polyfills
+
+core-js@2 has been removed from @rjsf/core. See more about [the rationale here](https://github.com/rjsf-team/react-jsonschema-form/pull/2211#issue-563700810).
+
+If you're using a framework like [Create React App](https://create-react-app.dev/docs/supported-browsers-features#supported-browsers), [Gatsby](https://www.gatsbyjs.com/docs/how-to/custom-configuration/browser-support/), [Next.js](https://nextjs.org/docs/basic-features/supported-browsers-features), or transpiling code through something like `@babel/preset-env`, polyfills are already included there and you won't have to do anything.
+
+If you were directly depending on @rjsf/core's @babel/runtime pulling in core-js@2, just `npm install core-js` and using a side effectful import at the top of your entry point (`import 'core-js'`) might be enough.
+
+For a slightly more elaborate setup, [@babel/preset-env](https://babeljs.io/docs/en/babel-preset-env#how-does-it-work) is probably a good second choice.
+
+From `@babel/preset-env`'s docs
+
+> We leverage [`browserslist`, `compat-table`, and `electron-to-chromium`] to maintain mappings of which version of our supported target environments gained support of a JavaScript syntax or browser feature, as well as a mapping of those syntaxes and features to Babel transform plugins and core-js polyfills.

mkdocs.yml

@@ -30,6 +30,7 @@ nav:
       - Theme-Specific Reference:
         - semantic-ui: api-reference/themes/semantic-ui/uiSchema.md
     - "<Form /> props": api-reference/form-props.md
+  - 3.x Migration: 3.x upgrade guide.md
 
 markdown_extensions:
   - toc:

packages/antd/babel.config.js

@@ -1,48 +1,3 @@
-const BABEL_ENV = process.env.BABEL_ENV;
+const defaultConfig = require('../../babel.config')
 
-const defaultPlugins = [];
-
-module.exports = {
-  "presets": [
-    [
-      "@babel/preset-env",
-      {
-        modules: ["cjs", "test"].includes(BABEL_ENV) ? "commonjs" : false,
-        targets:
-          BABEL_ENV === "test" ? { node: "current" } : { browsers: "defaults" },
-      },
-    ],
-    "@babel/preset-react"
-  ],
-  "plugins": [
-    "@babel/plugin-proposal-object-rest-spread",
-    "@babel/plugin-proposal-class-properties",
-    [
-      "@babel/plugin-transform-runtime",
-      {
-        "corejs": 2
-      }
-    ]
-  ],
-  "env": {
-    cjs: {
-      plugins: defaultPlugins,
-      ignore: ['test/**/*.js']
-    },
-    umd: {
-      plugins: defaultPlugins,
-      ignore: ['test/**/*.js']
-    },
-    es: {
-      plugins: [
-        ...defaultPlugins,
-        ['@babel/plugin-transform-runtime', { useESModules: true, corejs: 2 }]
-      ],
-      ignore: ['test/**/*.js']
-    },
-    test: {
-      plugins: defaultPlugins,
-      ignore: []
-    }
-  }
-};
+module.exports = defaultConfig

packages/antd/package.json

@@ -28,11 +28,9 @@
   },
   "peerDependencies": {
     "@ant-design/icons": "^4.0.0",
-    "@babel/runtime-corejs2": "^7.10.3",
     "@rjsf/core": "^2.0.0",
     "antd": "^4.0.0",
     "antd-dayjs-webpack-plugin": "1.0.0",
-    "core-js": "^2.5.7",
     "dayjs": "^1.8.0",
     "lodash": "^4.17.15",
     "react": ">=16"
@@ -42,20 +40,16 @@
     "@babel/cli": "^7.4.4",
     "@babel/core": "^7.4.5",
     "@babel/plugin-proposal-class-properties": "^7.5.5",
-    "@babel/plugin-proposal-object-rest-spread": "^7.5.5",
     "@babel/plugin-transform-react-jsx": "^7.3.0",
-    "@babel/plugin-transform-runtime": "^7.5.5",
     "@babel/preset-env": "^7.10.3",
     "@babel/preset-react": "^7.0.0",
     "@babel/register": "^7.4.4",
-    "@babel/runtime-corejs2": "^7.10.3",
     "@rjsf/core": "^2.5.1",
     "antd": "^4.0.0",
     "atob": "^2.0.3",
     "babel-eslint": "^10.0.1",
     "babel-loader": "^8.0.6",
     "concurrently": "^5.1.0",
-    "core-js": "^2.5.7",
     "cross-env": "^2.0.1",
     "css-loader": "^3.2.0",
     "dayjs": "^1.8.0",
@@ -70,7 +64,6 @@
     "less-loader": "^5.0.0",
     "lodash": "^4.17.15",
     "react": "^16.8.6",
-    "react-app-polyfill": "^1.0.4",
     "react-dom": "^16.8.6",
     "react-test-renderer": "^16.13.1",
     "rimraf": "^3.0.2",

packages/bootstrap-4/package.json

@@ -25,9 +25,7 @@
   "devDependencies": {
     "@babel/core": "^7.0.0-0",
     "@babel/plugin-proposal-class-properties": "^7.5.5",
-    "@babel/plugin-proposal-object-rest-spread": "^7.5.5",
     "@babel/plugin-transform-modules-commonjs": "^7.8.3",
-    "@babel/plugin-transform-runtime": "^7.5.5",
     "@babel/preset-env": "^7.5.5",
     "@babel/preset-react": "^7.0.0",
     "@rjsf/core": "^2.5.1",

packages/core/babel.config.js

@@ -1,44 +1,3 @@
-const BABEL_ENV = process.env.BABEL_ENV;
+const defaultConfig = require('../../babel.config')
 
-const defaultPlugins = [
-  '@babel/plugin-proposal-class-properties',
-  '@babel/plugin-proposal-object-rest-spread',
-  '@babel/plugin-proposal-optional-chaining',
-  // IE 11 support
-  '@babel/plugin-transform-object-assign'
-];
-
-module.exports = {
-  presets: [
-    [
-      "@babel/preset-env",
-      {
-        modules: ["cjs", "test"].includes(BABEL_ENV) ? "commonjs" : false,
-        targets:
-          BABEL_ENV === "test" ? { node: "current" } : { browsers: "defaults" },
-      },
-    ],
-    "@babel/preset-react",
-  ],
-  env: {
-    cjs: {
-      plugins: defaultPlugins,
-      ignore: ['test/**/*.js']
-    },
-    umd: {
-      plugins: defaultPlugins,
-      ignore: ['test/**/*.js']
-    },
-    es: {
-      plugins: [
-        ...defaultPlugins,
-        ['@babel/plugin-transform-runtime', { useESModules: true, corejs: 2 }]
-      ],
-      ignore: ['test/**/*.js']
-    },
-    test: {
-      plugins: defaultPlugins,
-      ignore: []
-    }
-  },
-};
+module.exports = defaultConfig

packages/core/package.json

@@ -40,27 +40,23 @@
     "react": ">=16"
   },
   "dependencies": {
-    "@babel/runtime-corejs2": "^7.8.7",
     "@types/json-schema": "^7.0.4",
     "ajv": "^6.7.0",
-    "core-js": "^2.5.7",
+    "core-js-pure": "^3.6.5",
     "json-schema-merge-allof": "^0.6.0",
     "jsonpointer": "^4.0.1",
     "lodash": "^4.17.15",
     "prop-types": "^15.7.2",
-    "react-app-polyfill": "^1.0.4",
     "react-is": "^16.9.0",
     "shortid": "^2.2.14"
   },
   "devDependencies": {
     "@babel/cli": "^7.4.4",
     "@babel/core": "^7.4.5",
     "@babel/plugin-proposal-class-properties": "^7.4.4",
-    "@babel/plugin-proposal-object-rest-spread": "^7.4.4",
     "@babel/plugin-proposal-optional-chaining": "^7.8.3",
     "@babel/plugin-transform-object-assign": "^7.8.3",
     "@babel/plugin-transform-react-jsx": "^7.3.0",
-    "@babel/plugin-transform-runtime": "^7.4.4",
     "@babel/preset-env": "^7.4.5",
     "@babel/preset-react": "^7.0.0",
     "@babel/register": "^7.4.4",

packages/core/src/components/fields/ArrayField.js

@@ -1,7 +1,7 @@
 import AddButton from "../AddButton";
 import IconButton from "../IconButton";
 import React, { Component } from "react";
-import includes from "core-js/library/fn/array/includes";
+import includes from "core-js-pure/es/array/includes";
 import * as types from "../../types";
 
 import {