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Provide TypeScript helper function to convert metadatum into JS objects.
 Throws whenever the conversion isn't possible. This should work for CIP-0025's media NFT and probably few other metadata format. But it is unsound in the general cases.
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3 files changed

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‎clients/TypeScript/packages/client/src/util.ts‎

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Original file line numberDiff line numberDiff line change
@@ -9,6 +9,8 @@ import {
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BlockMary,
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BlockShelley,
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EpochBoundaryBlock,
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Metadatum,
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MetadatumMap,
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Point,
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ProtocolParametersAlonzo,
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ProtocolParametersBabbage,
@@ -176,6 +178,56 @@ export function eventEmitterToGenerator <T> (eventEmitter: EventEmitter, eventNa
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}
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}
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/** Convert a CBOR-description as raw JSON object, or throw if given an invalid
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* representation. This function is meant to use for converting transaction's
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* metadata into plain JSON in context where that conversion is expected to work.
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*
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* It isn't generally possible to do so because not every CBOR object have a 1:1
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* mapping to a JSON object. This function should therefore work for metadata
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* coming from CIP-0025, and likely a few other standards but is unsound in the
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* general case and isn't expected to work on *any* metadata that can be found on
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* chain.
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*
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* @category Helper */
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export function unsafeMetadatumAsJSON (metadatum: Metadatum): any {
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function fromMetadatum (o: Metadatum): any {
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if (Object.keys(o).length > 1) {
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throw new Error('Malformed metadatum object. A JSON object that describes CBOR encoded datum is expected.')
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}
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if ('int' in o) {
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return o.int
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} else if ('string' in o) {
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return o.string
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} else if ('bytes' in o) {
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return Buffer.from(o.bytes, 'hex')
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} else if ('list' in o) {
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return o.list.map(fromMetadatum)
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} else if ('map' in o) {
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return o.map.reduce(fromMetadatumMap, {})
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} else {
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const type = Object.keys(o)[0]
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const msg = `Unexpected metadatum type '${type}'.`
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let hint = ''
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if (Number.isInteger(Number.parseInt(type, 10))) {
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hint = ' Hint: this function expects metadatum objects without metadatum label.'
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}
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throw new Error(`${msg}${hint}`)
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}
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}
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function fromMetadatumMap (acc: { [k: string]: any }, { k, v }: MetadatumMap) {
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const kStr = fromMetadatum(k)
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if (typeof kStr !== 'string') {
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throw new Error(`Invalid non-string key: ${k}.`)
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}
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acc[kStr] = fromMetadatum(v)
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return acc
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}
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return fromMetadatum(metadatum)
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}
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/** @category Helper */
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export const isAllegraBlock = (block: Block): block is { allegra: BlockAllegra } =>
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(block as { allegra: BlockAllegra }).allegra !== undefined

‎clients/TypeScript/packages/client/test/util.test.ts‎

Lines changed: 170 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@ import {
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TxOut
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} from '@cardano-ogmios/schema'
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import { EventEmitter } from 'events'
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import { safeJSON, eventEmitterToGenerator } from '../src'
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import { safeJSON, eventEmitterToGenerator, unsafeMetadatumAsJSON } from '../src'
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describe('util', () => {
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describe('eventToGenerator', () => {
@@ -253,4 +253,173 @@ describe('util', () => {
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})
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})
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})
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describe('unsafeMetadatumAsJSON', () => {
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it('primitives :: int', () => {
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const json = unsafeMetadatumAsJSON({
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int: 42n
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})
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expect(json as number).toEqual(42n)
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})
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it('primitives :: string', () => {
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const json = unsafeMetadatumAsJSON({
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string: 'foo'
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})
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expect(json as string).toEqual('foo')
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})
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it('primitives :: bytes', () => {
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const json = unsafeMetadatumAsJSON({
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bytes: '626172'
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})
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expect(json as Buffer).toEqual(Buffer.from('bar'))
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})
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it('primitives :: list', () => {
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const json = unsafeMetadatumAsJSON({
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list: [{ int: 42n }]
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})
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expect(json as Array<any>).toEqual([42n])
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})
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it('primitives :: map', () => {
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const json = unsafeMetadatumAsJSON({
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map: [{ k: { string: 'foo' }, v: { int: 42n } }]
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})
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expect(json as Object).toEqual({ foo: 42n })
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})
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it('compound', () => {
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const json = unsafeMetadatumAsJSON({
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map: [
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{
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k: {
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string: 'f0ff48bbb7bbe9d59a40f1ce90e9e9d0ff5002ec48f232b49ca0fb9a'
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},
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v: {
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map: [
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{
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k: {
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string: 'reactant'
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},
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v: {
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map: [
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{
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k: {
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string: 'name'
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},
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v: {
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string: '$reactant'
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}
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},
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{
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k: {
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string: 'description'
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},
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v: {
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string: 'The Handle Standard'
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}
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},
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{
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k: {
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string: 'website'
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},
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v: {
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string: 'https://adahandle.com'
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}
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},
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{
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k: {
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string: 'image'
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},
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v: {
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string: 'ipfs://QmWLeos8yGBE7o69wUxGYcXmS8qgc4TiyZ4VHcGmfkBiY3'
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}
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},
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{
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k: {
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string: 'core'
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},
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v: {
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map: [
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{
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k: {
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string: 'og'
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},
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v: {
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int: 0n
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}
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},
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{
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k: {
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string: 'termsofuse'
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},
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v: {
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string: 'https://adahandle.com/tou'
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}
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},
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{
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k: {
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string: 'handleEncoding'
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},
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v: {
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string: 'utf-8'
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}
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},
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{
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k: {
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string: 'prefix'
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},
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v: {
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string: '$'
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}
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},
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{
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k: {
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string: 'version'
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},
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v: {
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int: 0n
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}
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}
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]
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}
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},
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{
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k: {
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string: 'augmentations'
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},
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v: {
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list: []
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}
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}
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]
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}
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}
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]
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}
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}
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]
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})
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expect(json as Object).toEqual({
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f0ff48bbb7bbe9d59a40f1ce90e9e9d0ff5002ec48f232b49ca0fb9a: {
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reactant: {
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augmentations: [],
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core: {
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handleEncoding: 'utf-8',
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og: 0n,
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prefix: '$',
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termsofuse: 'https://adahandle.com/tou',
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version: 0n
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},
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description: 'The Handle Standard',
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image: 'ipfs://QmWLeos8yGBE7o69wUxGYcXmS8qgc4TiyZ4VHcGmfkBiY3',
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name: '$reactant',
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website: 'https://adahandle.com'
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}
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}
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})
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})
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})
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})

‎clients/TypeScript/tsconfig.json‎

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@@ -2,7 +2,7 @@
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"compilerOptions": {
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"composite": true,
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"module": "commonjs",
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"target": "es2017",
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"target": "es2020",
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"esModuleInterop": true,
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"declaration": true,
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"declarationMap": true,

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