Add inverse option to core-js-compat

CHANGELOG.md

@@ -1,6 +1,6 @@
 ## Changelog
 ##### Unreleased
-- Nothing
+- Added `inverse` option to `core-js-compat`, [#1119](https://github.com/zloirock/core-js/issues/1119)
 
 ##### [3.25.5 - 2022.10.04](https://github.com/zloirock/core-js/releases/tag/v3.25.5)
 - Fixed regression with an error on reuse of some built-in methods from another realm, [#1133](https://github.com/zloirock/core-js/issues/1133)

packages/core-js-compat/README.md

@@ -12,19 +12,20 @@
 import compat from 'core-js-compat';
 
 const {
-  list,                         // array of required modules
-  targets,                      // object with targets for each module
+  list,                       // array of required modules
+  targets,                    // object with targets for each module
 } = compat({
-  targets: '> 1%',              // browserslist query or object of minimum environment versions to support, see below
-  modules: [                    // optional list / filter of modules - regex, sting or an array of them:
-    'core-js/actual',           // - an entry point
-    'esnext.array.unique-by',   // - a module name (or just a start of a module name)
-    /^web\./,                   // - regex that a module name must satisfy
+  targets: '> 1%',            // browserslist query or object of minimum environment versions to support, see below
+  modules: [                  // optional list / filter of modules - regex, sting or an array of them:
+    'core-js/actual',         // - an entry point
+    'esnext.array.unique-by', // - a module name (or just a start of a module name)
+    /^web\./,                 // - regex that a module name must satisfy
   ],
-  exclude: [                    // optional list / filter of modules to exclude, the signature is similar to `modules` option
+  exclude: [                  // optional list / filter of modules to exclude, the signature is similar to `modules` option
     'web.atob',
   ],
-  version: '3.25',              // used `core-js` version, by default - the latest
+  version: '3.25',            // used `core-js` version, by default - the latest
+  inverse: false,             // inverse of the result - shows modules that are NOT required for the target environment
 });
 
 console.log(targets);

packages/core-js-compat/compat.js

@@ -54,8 +54,10 @@ module.exports = function ({
   exclude = [],
   targets = null,
   version = null,
+  inverse = false,
 } = {}) {
   if (modules == null) modules = filter;
+  inverse = !!inverse;
 
   const parsedTargets = targets ? targetsParser(targets) : null;
 
@@ -72,12 +74,12 @@ module.exports = function ({
 
   modules = intersection(modules, version ? getModulesListForTargetVersion(version) : allModules);
 
-  modules = filterOutStabilizedProposals(modules);
+  if (!inverse) modules = filterOutStabilizedProposals(modules);
 
   for (const key of modules) {
     const check = checkModule(key, parsedTargets);
 
-    if (check.required) {
+    if (check.required ^ inverse) {
       result.list.push(key);
       result.targets[key] = check.targets;
     }

tests/compat-tools/compat.mjs

@@ -1,4 +1,4 @@
-import { deepEqual } from 'assert/strict';
+import { deepEqual, ok } from 'assert/strict';
 import compat from 'core-js-compat/compat.js';
 
 deepEqual(compat({
@@ -119,4 +119,15 @@ deepEqual(compat({
   },
 }, 'some targets');
 
+const { list: inverted1 } = compat({ targets: { esmodules: true }, inverse: true });
+
+ok(inverted1.includes('es.symbol.iterator'), 'inverse #1');
+ok(!inverted1.includes('esnext.iterator.from'), 'inverse #2');
+ok(!inverted1.includes('esnext.array.at'), 'inverse #3');
+
+const { list: inverted2 } = compat({ modules: 'core-js/es/math', targets: { esmodules: true }, inverse: true });
+
+ok(inverted2.includes('es.math.acosh'), 'inverse #4');
+ok(!inverted2.includes('es.map'), 'inverse #5');
+
 echo(chalk.green('compat tool tested'));