[WIP] Well‑formed JSON.stringify (#681)

[WIP] Well‑formed `JSON.stringify`

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## Changelog
 ##### Unreleased
-- Fixed `Math.signbit`, [#687](https://github.com/zloirock/core-js/issues/687), thanks @chicoxyzzy
+- Added [well-formed `JSON.stringify`](https://github.com/tc39/proposal-well-formed-stringify), ES2019 feature, thanks [@ExE-Boss](https://github.com/ExE-Boss) and [@WebReflection](https://github.com/WebReflection) for the idea
+- Fixed `Math.signbit`, [#687](https://github.com/zloirock/core-js/issues/687), thanks [@chicoxyzzy](https://github.com/chicoxyzzy)
 
 ##### 3.3.6 - 2019.11.01
 - Don't detect Chakra-based Edge as Chrome in the `userAgent` parsing

README.md

@@ -85,6 +85,7 @@ Promise.resolve(32).then(x => console.log(x)); // => 32
     - [ECMAScript: Collections](#ecmascript-collections)
     - [ECMAScript: Typed Arrays](#ecmascript-typed-arrays)
     - [ECMAScript: Reflect](#ecmascript-reflect)
+    - [ECMAScript: JSON](#ecmascript-json)
     - [ECMAScript: globalThis](#ecmascript-globalthis)
   - [ECMAScript proposals](#ecmascript-proposals)
     - [stage 4 proposals](#stage-4-proposals)
@@ -1068,7 +1069,7 @@ setTimeout(() => promise.catch(() => {}), 1e3);
 ```
 
 #### ECMAScript: Symbol
-Modules [`es.symbol`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.js), [`es.symbol.async-iterator`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.async-iterator.js), [`es.symbol.description`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.description.js), [`es.symbol.has-instance`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.has-instance.js), [`es.symbol.is-concat-spreadable`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.is-concat-spreadable.js), [`es.symbol.iterator`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.iterator.js), [`es.symbol.match`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.match.js), [`es.symbol.replace`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.replace.js), [`es.symbol.search`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.search.js), [`es.symbol.species`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.species.js), [`es.symbol.split`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.split.js), [`es.symbol.to-primitive`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.to-primitive.js), [`es.symbol.to-string-tag`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.to-string-tag.js), [`es.symbol.unscopables`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.symbol.unscopables.js), [`es.math.to-string-tag`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.math.to-string-tag.js), [`es.json.to-string-tag`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.json.to-string-tag.js).
+Modules [`es.symbol`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.js), [`es.symbol.async-iterator`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.async-iterator.js), [`es.symbol.description`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.description.js), [`es.symbol.has-instance`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.has-instance.js), [`es.symbol.is-concat-spreadable`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.is-concat-spreadable.js), [`es.symbol.iterator`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.iterator.js), [`es.symbol.match`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.match.js), [`es.symbol.replace`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.replace.js), [`es.symbol.search`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.search.js), [`es.symbol.species`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.species.js), [`es.symbol.split`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.split.js), [`es.symbol.to-primitive`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.to-primitive.js), [`es.symbol.to-string-tag`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.to-string-tag.js), [`es.symbol.unscopables`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.symbol.unscopables.js), [`es.math.to-string-tag`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.math.to-string-tag.js).
 ```js
 class Symbol {
   constructor(description?): symbol;
@@ -1105,10 +1106,6 @@ class Object {
   static getOwnPropertyNames(object: any): Array<string>;
   propertyIsEnumerable(key: PropertyKey): boolean;
 }
-
-namespace JSON {
-  stringify(target: any, replacer?: Function | Array, space?: string | number): string | void;
-}
 ```
 [*CommonJS entry points:*](#commonjs-api)
 ```
@@ -1130,7 +1127,6 @@ core-js(-pure)/es|stable|features/symbol/for
 core-js(-pure)/es|stable|features/symbol/key-for
 core-js(-pure)/es|stable|features/object/get-own-property-symbols
 core-js(-pure)/es|stable|features/math/to-string-tag
-core-js(-pure)/es|stable|features/json/to-string-tag
 ```
 [*Basic example*](http://goo.gl/BbvWFc):
 ```js
@@ -1594,6 +1590,26 @@ let instance = Reflect.construct(C, [20, 22]);
 instance.c; // => 42
 ```
 
+#### ECMAScript: JSON
+Since `JSON` object is missed only in very old engines like IE7-, `core-js` does not provide a full `JSON` polyfill, however, fix already existing implementations by the current standard, for example, [well-formed `JSON.stringify`](https://github.com/tc39/proposal-well-formed-stringify). `JSON` also fixed in other modules - for example, `Symbol` polyfill fixes `JSON.stringify` for correct work with symbols.
+
+Module [`es.json.to-string-tag`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.json.to-string-tag.js) and [`es.json.stringify`](https://github.com/zloirock/core-js/blob/v3.4.0/packages/core-js/modules/es.json.stringify.js).
+```js
+namespace JSON {
+  stringify(target: any, replacer?: Function | Array, space?: string | number): string | void;
+  @@toStringTag: 'JSON';
+}
+```
+[*CommonJS entry points:*](#commonjs-api)
+```js
+core-js(-pure)/es|stable|features/json/stringify
+core-js(-pure)/es|stable|features/json/to-string-tag
+```
+[*Examples*](http://es6.zloirock.ru/#log(JSON.stringify(%7B%20'%F0%A0%AE%B7'%3A%20%5B'%5CuDF06%5CuD834'%5D%20%7D))%3B%20%2F%2F%20%3D%3E%20'%7B%22%F0%A0%AE%B7%22%3A%5B%22%5C%5Cudf06%5C%5Cud834%22%5D%7D'):
+```js
+JSON.stringify({ '𠮷': ['\uDF06\uD834'] }); // => '{"𠮷":["\\udf06\\ud834"]}'
+```
+
 #### ECMAScript: globalThis
 Module [`es.global-this`](https://github.com/zloirock/core-js/blob/v3.3.6/packages/core-js/modules/es.global-this.js).
 ```js

packages/core-js-compat/src/data.js

@@ -337,6 +337,11 @@ const data = {
     firefox: '65',
     safari: '12.1',
   },
+  'es.json.stringify': {
+    chrome: '72',
+    firefox: '64',
+    safari: '12.1',
+  },
   'es.json.to-string-tag': {
     edge: '15',
     chrome: '50',

packages/core-js-compat/src/modules-by-versions.js

@@ -44,4 +44,7 @@ module.exports = {
     'esnext.map.upsert',
     'esnext.weak-map.upsert',
   ],
+  3.4: [
+    'es.json.stringify',
+  ],
 };

packages/core-js/es/json/stringify.js

@@ -1,6 +1,9 @@
+require('../../modules/es.json.stringify');
 var core = require('../../internals/path');
-var $JSON = core.JSON || (core.JSON = { stringify: JSON.stringify });
 
-module.exports = function stringify(it) { // eslint-disable-line no-unused-vars
-  return $JSON.stringify.apply($JSON, arguments);
+if (!core.JSON) core.JSON = { stringify: JSON.stringify };
+
+// eslint-disable-next-line no-unused-vars
+module.exports = function stringify(it, replacer, space) {
+  return core.JSON.stringify.apply(null, arguments);
 };

packages/core-js/modules/es.json.stringify.js

@@ -0,0 +1,32 @@
+var $ = require('../internals/export');
+var getBuiltIn = require('../internals/get-built-in');
+var fails = require('../internals/fails');
+
+var $stringify = getBuiltIn('JSON', 'stringify');
+var re = /[\uD800-\uDFFF]/g;
+var low = /^[\uD800-\uDBFF]$/;
+var hi = /^[\uDC00-\uDFFF]$/;
+
+var fix = function (match, offset, string) {
+  var prev = string.charAt(offset - 1);
+  var next = string.charAt(offset + 1);
+  if ((low.test(match) && !hi.test(next)) || (hi.test(match) && !low.test(prev))) {
+    return '\\u' + match.charCodeAt(0).toString(16);
+  } return match;
+};
+
+var FORCED = fails(function () {
+  return $stringify('\uDF06\uD834') !== '"\\udf06\\ud834"'
+    || $stringify('\uDEAD') !== '"\\udead"';
+});
+
+if ($stringify) {
+  // https://github.com/tc39/proposal-well-formed-stringify
+  $({ target: 'JSON', stat: true, forced: FORCED }, {
+    // eslint-disable-next-line no-unused-vars
+    stringify: function stringify(it, replacer, space) {
+      var result = $stringify.apply(null, arguments);
+      return typeof result == 'string' ? result.replace(re, fix) : result;
+    }
+  });
+}

packages/core-js/modules/es.symbol.js

@@ -1,6 +1,7 @@
 'use strict';
 var $ = require('../internals/export');
 var global = require('../internals/global');
+var getBuiltIn = require('../internals/get-built-in');
 var IS_PURE = require('../internals/is-pure');
 var DESCRIPTORS = require('../internals/descriptors');
 var NATIVE_SYMBOL = require('../internals/native-symbol');
@@ -42,8 +43,7 @@ var setInternalState = InternalStateModule.set;
 var getInternalState = InternalStateModule.getterFor(SYMBOL);
 var ObjectPrototype = Object[PROTOTYPE];
 var $Symbol = global.Symbol;
-var JSON = global.JSON;
-var nativeJSONStringify = JSON && JSON.stringify;
+var $stringify = getBuiltIn('JSON', 'stringify');
 var nativeGetOwnPropertyDescriptor = getOwnPropertyDescriptorModule.f;
 var nativeDefineProperty = definePropertyModule.f;
 var nativeGetOwnPropertyNames = getOwnPropertyNamesExternal.f;
@@ -264,30 +264,35 @@ $({ target: 'Object', stat: true, forced: fails(function () { getOwnPropertySymb
 
 // `JSON.stringify` method behavior with symbols
 // https://tc39.github.io/ecma262/#sec-json.stringify
-JSON && $({ target: 'JSON', stat: true, forced: !NATIVE_SYMBOL || fails(function () {
-  var symbol = $Symbol();
-  // MS Edge converts symbol values to JSON as {}
-  return nativeJSONStringify([symbol]) != '[null]'
-    // WebKit converts symbol values to JSON as null
-    || nativeJSONStringify({ a: symbol }) != '{}'
-    // V8 throws on boxed symbols
-    || nativeJSONStringify(Object(symbol)) != '{}';
-}) }, {
-  stringify: function stringify(it) {
-    var args = [it];
-    var index = 1;
-    var replacer, $replacer;
-    while (arguments.length > index) args.push(arguments[index++]);
-    $replacer = replacer = args[1];
-    if (!isObject(replacer) && it === undefined || isSymbol(it)) return; // IE8 returns string on undefined
-    if (!isArray(replacer)) replacer = function (key, value) {
-      if (typeof $replacer == 'function') value = $replacer.call(this, key, value);
-      if (!isSymbol(value)) return value;
-    };
-    args[1] = replacer;
-    return nativeJSONStringify.apply(JSON, args);
-  }
-});
+if ($stringify) {
+  var FORCED_JSON_STRINGIFY = !NATIVE_SYMBOL || fails(function () {
+    var symbol = $Symbol();
+    // MS Edge converts symbol values to JSON as {}
+    return $stringify([symbol]) != '[null]'
+      // WebKit converts symbol values to JSON as null
+      || $stringify({ a: symbol }) != '{}'
+      // V8 throws on boxed symbols
+      || $stringify(Object(symbol)) != '{}';
+  });
+
+  $({ target: 'JSON', stat: true, forced: FORCED_JSON_STRINGIFY }, {
+    // eslint-disable-next-line no-unused-vars
+    stringify: function stringify(it, replacer, space) {
+      var args = [it];
+      var index = 1;
+      var $replacer;
+      while (arguments.length > index) args.push(arguments[index++]);
+      $replacer = replacer;
+      if (!isObject(replacer) && it === undefined || isSymbol(it)) return; // IE8 returns string on undefined
+      if (!isArray(replacer)) replacer = function (key, value) {
+        if (typeof $replacer == 'function') value = $replacer.call(this, key, value);
+        if (!isSymbol(value)) return value;
+      };
+      args[1] = replacer;
+      return $stringify.apply(null, args);
+    }
+  });
+}
 
 // `Symbol.prototype[@@toPrimitive]` method
 // https://tc39.github.io/ecma262/#sec-symbol.prototype-@@toprimitive

tests/compat/tests.js

@@ -439,6 +439,10 @@ GLOBAL.tests = {
   'es.global-this': function () {
     return globalThis;
   },
+  'es.json.stringify': function () {
+    return JSON.stringify('\uDF06\uD834') === '"\\udf06\\ud834"'
+      && JSON.stringify('\uDEAD') === '"\\udead"';
+  },
   'es.json.to-string-tag': [SYMBOLS_SUPPORT, function () {
     return JSON[Symbol.toStringTag];
   }],

tests/pure/es.json.stringify.js

@@ -0,0 +1,20 @@
+import { GLOBAL } from '../helpers/constants';
+import stringify from 'core-js/es/json/stringify';
+
+if (GLOBAL.JSON) {
+  QUnit.test('Well‑formed JSON.stringify', assert => {
+    assert.isFunction(stringify);
+    assert.arity(stringify, 3);
+    assert.name(stringify, 'stringify');
+
+    assert.same(stringify({ foo: 'bar' }), '{"foo":"bar"}', 'basic');
+    assert.same(stringify('\uDEAD'), '"\\udead"', 'r1');
+    assert.same(stringify('\uDF06\uD834'), '"\\udf06\\ud834"', 'r2');
+    assert.same(stringify('\uDF06ab\uD834'), '"\\udf06ab\\ud834"', 'r3');
+    assert.same(stringify('𠮷'), '"𠮷"', 'r4');
+    assert.same(stringify('\uD834\uDF06'), '"𝌆"', 'r5');
+    assert.same(stringify('\uD834\uD834\uDF06'), '"\\ud834𝌆"', 'r6');
+    assert.same(stringify('\uD834\uDF06\uDF06'), '"𝌆\\udf06"', 'r7');
+    assert.same(stringify({ '𠮷': ['\uDF06\uD834'] }), '{"𠮷":["\\udf06\\ud834"]}', 'r8');
+  });
+}

tests/pure/index.js

@@ -35,6 +35,7 @@ import './es.date.to-json';
 import './es.function.bind';
 import './es.function.has-instance';
 import './es.global-this';
+import './es.json.stringify';
 import './es.map';
 import './es.math.acosh';
 import './es.math.asinh';

tests/tests/es.json.stringify.js

@@ -0,0 +1,21 @@
+import { GLOBAL } from '../helpers/constants';
+
+if (GLOBAL.JSON) {
+  QUnit.test('Well‑formed JSON.stringify', assert => {
+    const { stringify } = JSON;
+    assert.isFunction(stringify);
+    assert.arity(stringify, 3);
+    assert.name(stringify, 'stringify');
+    assert.looksNative(stringify);
+
+    assert.same(stringify({ foo: 'bar' }), '{"foo":"bar"}', 'basic');
+    assert.same(stringify('\uDEAD'), '"\\udead"', 'r1');
+    assert.same(stringify('\uDF06\uD834'), '"\\udf06\\ud834"', 'r2');
+    assert.same(stringify('\uDF06ab\uD834'), '"\\udf06ab\\ud834"', 'r3');
+    assert.same(stringify('𠮷'), '"𠮷"', 'r4');
+    assert.same(stringify('\uD834\uDF06'), '"𝌆"', 'r5');
+    assert.same(stringify('\uD834\uD834\uDF06'), '"\\ud834𝌆"', 'r6');
+    assert.same(stringify('\uD834\uDF06\uDF06'), '"𝌆\\udf06"', 'r7');
+    assert.same(stringify({ '𠮷': ['\uDF06\uD834'] }), '{"𠮷":["\\udf06\\ud834"]}', 'r8');
+  });
+}

tests/tests/index.js

@@ -35,6 +35,7 @@ import './es.function.bind';
 import './es.function.has-instance';
 import './es.function.name';
 import './es.global-this';
+import './es.json.stringify';
 import './es.map';
 import './es.math.acosh';
 import './es.math.asinh';