Support for decimal.js. Support for Prisma.Decimal.

README.md

@@ -217,6 +217,7 @@ Superjson supports many extra types which JSON does not. You can serialize all t
 | `Set`       | ❌                           | ✅                       |
 | `Map`       | ❌                           | ✅                       |
 | `Error`     | ❌                           | ✅                       |
+| `Decimal`   | ❌                           | ✅                       |
 
 ## Contributors ✨
 

package.json

@@ -67,6 +67,7 @@
   },
   "dependencies": {
     "debug": "^4.3.1",
+    "decimal.js": "^10.3.1",
     "lodash.clonedeep": "^4.5.0"
   },
   "resolutions": {

src/index.test.ts

@@ -13,6 +13,7 @@ import {
 } from './is';
 
 import { ObjectID } from 'mongodb';
+import Decimal from 'decimal.js';
 
 const isNode10 = process.version.indexOf('v10') === 0;
 
@@ -192,6 +193,20 @@ describe('stringify & parse', () => {
       },
     },
 
+    'works for Decimals': {
+      input: {
+        totalCost: new Decimal('199.99'),
+      },
+      output: {
+        totalCost: new Decimal('199.99').toJSON(),
+      },
+      outputAnnotations: {
+        values: {
+          totalCost: ['Decimal'],
+        },
+      },
+    },
+
     'works for Errors': {
       input: {
         e: new Error('epic fail'),

src/is.test.ts

@@ -1,3 +1,4 @@
+import Decimal from 'decimal.js';
 import {
   isArray,
   isBoolean,
@@ -11,6 +12,7 @@ import {
   isUndefined,
   isPlainObject,
   isTypedArray,
+  isDecimal,
 } from './is';
 
 test('Basic true tests', () => {
@@ -29,6 +31,7 @@ test('Basic true tests', () => {
   expect(isNumber(0)).toBe(true);
   expect(isNumber(1)).toBe(true);
   expect(isDate(new Date())).toBe(true);
+  expect(isDecimal(new Decimal('100.1'))).toBe(true);
   expect(isSymbol(Symbol())).toBe(true);
   expect(isTypedArray(new Uint8Array())).toBe(true);
 });
@@ -37,6 +40,7 @@ test('Basic false tests', () => {
   expect(isNumber(NaN)).toBe(false);
   expect(isDate(new Date('_'))).toBe(false);
   expect(isDate(NaN)).toBe(false);
+  expect(isDecimal(NaN)).toBe(false);
   expect(isUndefined(NaN)).toBe(false);
   expect(isNull(NaN)).toBe(false);
 

src/is.ts

@@ -1,3 +1,5 @@
+import Decimal from 'decimal.js';
+
 const getType = (payload: any): string =>
   Object.prototype.toString.call(payload).slice(8, -1);
 
@@ -84,3 +86,6 @@ export type TypedArray = InstanceType<TypedArrayConstructor>;
 
 export const isTypedArray = (payload: any): payload is TypedArray =>
   ArrayBuffer.isView(payload) && !(payload instanceof DataView);
+
+export const isDecimal = (payload: any): payload is Decimal =>
+  Decimal.isDecimal(payload);

src/transformer.ts

@@ -11,13 +11,15 @@ import {
   isArray,
   isError,
   isTypedArray,
+  isDecimal,
   TypedArrayConstructor,
 } from './is';
 import { ClassRegistry } from './class-registry';
 import { SymbolRegistry } from './symbol-registry';
 import { CustomTransformerRegistry } from './custom-transformer-registry';
 import { allowedErrorProps } from './error-props';
 import { findArr } from './util';
+import Decimal from 'decimal.js';
 
 export type PrimitiveTypeAnnotation = 'number' | 'undefined' | 'bigint';
 
@@ -28,7 +30,7 @@ type ClassTypeAnnotation = ['class', string];
 type SymbolTypeAnnotation = ['symbol', string];
 type CustomTypeAnnotation = ['custom', string];
 
-type SimpleTypeAnnotation = LeafTypeAnnotation | 'map' | 'set';
+type SimpleTypeAnnotation = LeafTypeAnnotation | 'map' | 'set' | 'Decimal';
 
 type CompositeTypeAnnotation =
   | TypedArrayAnnotation
@@ -79,7 +81,12 @@ const simpleRules = [
     v => v.toISOString(),
     v => new Date(v)
   ),
-
+  simpleTransformation(
+    isDecimal,
+    'Decimal',
+    v => v.toJSON(),
+    v => new Decimal(v)
+  ),
   simpleTransformation(
     isError,
     'Error',

src/types.ts

@@ -1,5 +1,6 @@
 import { TypeAnnotation } from './transformer';
 import { MinimisedTree, ReferentialEqualityAnnotations } from './plainer';
+import Decimal from 'decimal.js';
 
 export type Class = { new (...args: any[]): any };
 
@@ -23,7 +24,8 @@ export type SerializableJSONValue =
   | bigint
   | Date
   | ClassInstance
-  | RegExp;
+  | RegExp
+  | typeof Decimal;
 
 export type SuperJSONValue =
   | JSONValue

yarn.lock

@@ -2507,6 +2507,11 @@ decimal.js@^10.2.0:
   resolved "https://registry.yarnpkg.com/decimal.js/-/decimal.js-10.2.1.tgz#238ae7b0f0c793d3e3cea410108b35a2c01426a3"
   integrity sha512-KaL7+6Fw6i5A2XSnsbhm/6B+NuEA7TZ4vqxnd5tXz9sbKtrN9Srj8ab4vKVdK8YAqZO9P1kg45Y6YLoduPf+kw==
 
+decimal.js@^10.3.1:
+  version "10.3.1"
+  resolved "https://registry.yarnpkg.com/decimal.js/-/decimal.js-10.3.1.tgz#d8c3a444a9c6774ba60ca6ad7261c3a94fd5e783"
+  integrity sha512-V0pfhfr8suzyPGOx3nmq4aHqabehUZn6Ch9kyFpV79TGDTWFmHqUqXdabR7QHqxzrYolF4+tVmJhUG4OURg5dQ==
+
 decode-uri-component@^0.2.0:
   version "0.2.0"
   resolved "https://registry.yarnpkg.com/decode-uri-component/-/decode-uri-component-0.2.0.tgz"