fix: allow replacer and reviver to be null

src/parse.test.ts

@@ -69,7 +69,7 @@ test('number', function () {
   expect(parse('23')).toEqual(lln('23'))
   expect(parse('0')).toEqual(lln('0'))
   expect(parse('0e+2')).toEqual(lln('0e+2'))
-  expect(parse('0e+2').valueOf()).toEqual(0)
+  expect((parse('0e+2') as LosslessNumber).valueOf()).toEqual(0)
   expect(parse('0.0')).toEqual(lln('0.0'))
   expect(parse('-0')).toEqual(lln('-0'))
   expect(parse('2.3')).toEqual(lln('2.3'))
@@ -190,7 +190,8 @@ test('reviver - invoke callbacks with key/value and correct context', function (
 
   // convert LosslessNumbers to numbers for easy comparison with native JSON
   function toRegularJSON(json: unknown) {
-    return JSON.parse(stringify(json))
+    const str = stringify(json)
+    return str !== undefined ? JSON.parse(str) : undefined
   }
 
   function reviver(key: string, value: unknown): unknown {
@@ -211,6 +212,8 @@ test('reviver - invoke callbacks with key/value and correct context', function (
   const logsActual: Log[] = []
   parse(text, function (key, value) {
     logsActual.push({
+      // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+      // @ts-expect-error
       context: toRegularJSON(this),
       key,
       value: toRegularJSON(value)

src/parse.ts

@@ -27,7 +27,7 @@ import { GenericObject } from './types'
  */
 export function parse(
   text: string,
-  reviver?: Reviver,
+  reviver?: Reviver | null,
   parseNumber: NumberParser = parseLosslessNumber
 ): unknown {
   let i = 0
@@ -57,6 +57,7 @@ export function parse(
         const key = parseString()
         if (key === undefined) {
           throwObjectKeyExpected()
+          return // To make TS happy
         }
 
         skipWhitespace()
@@ -65,6 +66,7 @@ export function parse(
 
         if (value === undefined) {
           throwObjectValueExpected()
+          return // To make TS happy
         }
 
         // TODO: test deep equal instead of strict equal

src/stringify.test.ts

@@ -1,6 +1,6 @@
 import { test, expect } from 'vitest'
 import Decimal from 'decimal.js'
-import { LosslessNumber, stringify } from './index'
+import { LosslessNumber, NumberStringifier, stringify } from './index'
 import type { GenericObject } from './types'
 
 // helper function to create a lossless number
@@ -10,6 +10,8 @@ function lln(value: string) {
 
 test('stringify', function () {
   expect(stringify(undefined)).toEqual(undefined)
+  expect(stringify(function () {})).toEqual(undefined)
+  expect(stringify(Symbol('test'))).toEqual(undefined)
 
   expect(stringify(null)).toEqual('null')
 
@@ -106,9 +108,9 @@ test('stringify Date', function () {
 })
 
 test('stringify Decimal', function () {
-  const decimalStringifier = {
-    test: (value: string) => Decimal.isDecimal(value),
-    stringify: (value: string) => value.toString()
+  const decimalStringifier: NumberStringifier = {
+    test: (value: unknown) => Decimal.isDecimal(value),
+    stringify: (value: unknown) => (value as Decimal).toString()
   }
   const numberStringifiers = [decimalStringifier]
 
@@ -135,8 +137,8 @@ test('should not have a .toJSON method implemented', function () {
 
 test('should throw an error when the output of a number stringifier is not a number', function () {
   const wrongStringifier = {
-    test: (value: string) => typeof value === 'number',
-    stringify: (value: string) => 'oopsie' + value // <-- does not return a valid number
+    test: (value: unknown) => typeof value === 'number',
+    stringify: (value: unknown) => 'oopsie' + value // <-- does not return a valid number
   }
 
   expect(() => stringify([4], undefined, undefined, [wrongStringifier])).toThrow(
@@ -207,6 +209,8 @@ test('stringify with replacer function', function () {
 
   const logs: Log[] = []
   stringify(json, function (key, value) {
+    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+    // @ts-expect-error
     logs.push({ context: this, key, value })
     return value
   })

src/stringify.ts

@@ -37,7 +37,7 @@ import { isNumber } from './utils.js'
  */
 export function stringify(
   value: unknown,
-  replacer?: Replacer,
+  replacer?: Replacer | null,
   space?: number | string,
   numberStringifiers?: NumberStringifier[]
 ): string | undefined {
@@ -51,11 +51,11 @@ export function stringify(
   /**
    * Stringify a value
    */
-  function stringifyValue(value: unknown, indent: string): string | undefined {
+  function stringifyValue(value: unknown, indent: string | undefined): string | undefined {
     if (Array.isArray(numberStringifiers)) {
       const stringifier = numberStringifiers.find((item) => item.test(value))
       if (stringifier) {
-        const str = stringifier.stringify(value)
+        const str: unknown = stringifier.stringify(value)
         if (typeof str !== 'string' || !isNumber(str)) {
           throw new Error(
             'Invalid JSON number: ' +
@@ -109,7 +109,7 @@ export function stringify(
   /**
    * Stringify an array
    */
-  function stringifyArray(array: Array<unknown>, indent: string): string {
+  function stringifyArray(array: Array<unknown>, indent: string | undefined): string {
     if (array.length === 0) {
       return '[]'
     }
@@ -143,7 +143,10 @@ export function stringify(
   /**
    * Stringify an object
    */
-  function stringifyObject(object: GenericObject<unknown>, indent: string): string {
+  function stringifyObject(
+    object: GenericObject<unknown>,
+    indent: string | undefined
+  ): string | undefined {
     if (typeof object.toJSON === 'function') {
       return stringify(object.toJSON(), replacer, space, undefined)
     }

src/utils.ts

@@ -110,7 +110,7 @@ export function toSafeNumberOrThrow(
       ? unsafeReason && unsafeReason !== UnsafeNumberReason.truncate_float
       : unsafeReason
   ) {
-    const unsafeReasonText = unsafeReason.replace(/_\w+$/, '')
+    const unsafeReasonText = unsafeReason?.replace(/_\w+$/, '')
     throw new Error(
       'Cannot safely convert to number: ' +
         `the value '${value}' would ${unsafeReasonText} and become ${number}`

tsconfig.json

@@ -8,6 +8,7 @@
     "esModuleInterop": true,
     "allowJs": false,
     "checkJs": false,
+    "strict": true,
     "noImplicitAny": true,
     "declaration": true,
     "declarationDir": "lib/types",