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michaelficarramichaelficarra
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add prototype
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6 files changed

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6 files changed

+328
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lines changed

‎.gitignore

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/tsconfig.tsbuildinfo
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/node_modules
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/lib

‎package-lock.json

+28
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‎package.json

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{
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"private": true,
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"name": "proposal-iterator-chunking",
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"version": "1.0.0",
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"description": "",
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"main": "lib/index.js",
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"scripts": {
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"build": "tsc",
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"test": "node --test test"
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},
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"repository": {
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"type": "git",
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"url": "git+ssh://[email protected]/tc39/proposal-iterator-chunking.git"
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},
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"author": "Michael Ficarra",
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"bugs": {
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"url": "https://github.com/tc39/proposal-iterator-chunking/issues"
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},
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"homepage": "https://github.com/tc39/proposal-iterator-chunking#readme",
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"devDependencies": {
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"typescript": "5.2.2"
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}
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}

‎src/index.ts

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const IteratorPrototype = Object.getPrototypeOf(Object.getPrototypeOf([].values()))
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function liftIterator<A>(iter: Iterator<A>): Iterable<A> {
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return { [Symbol.iterator]() { return iter; } };
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}
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function* chunksImpl<A>(iter: Iterator<A>, chunkSize: number): Generator<Array<A>> {
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let buffer = [];
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for (const elem of liftIterator(iter)) {
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buffer.push(elem);
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if (buffer.length === chunkSize) {
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yield buffer;
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buffer = [];
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}
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}
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if (buffer.length > 0) {
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yield buffer;
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}
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}
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function chunks<A>(this: Iterator<A>, chunkSize: number): Generator<Array<A>>
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function chunks(this: unknown, chunkSize: unknown = 2): Generator<unknown> {
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if (
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typeof chunkSize !== 'number'
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|| chunkSize <= 0
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|| Math.floor(chunkSize) !== chunkSize
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|| chunkSize >= Math.pow(2, 53)
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) {
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throw new RangeError;
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}
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return chunksImpl(this as Iterator<unknown>, chunkSize)
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}
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function* windowsImpl<A>(iter: Iterator<A>, windowSize: number): Generator<Array<A>> {
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let buffer = [];
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for (const elem of liftIterator(iter)) {
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if (buffer.length === windowSize) {
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buffer.shift();
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}
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buffer.push(elem);
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if (buffer.length === windowSize) {
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yield buffer.slice();
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}
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}
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}
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function windows<A>(this: Iterator<A>, windowSize: number): Generator<Array<A>>
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function windows(this: unknown, windowSize: unknown = 2): Generator<unknown> {
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if (
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typeof windowSize !== 'number'
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|| windowSize <= 0
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|| Math.floor(windowSize) !== windowSize
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|| windowSize >= Math.pow(2, 53)
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) {
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throw new RangeError;
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}
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return windowsImpl(this as Iterator<unknown>, windowSize)
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}
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Object.defineProperty(IteratorPrototype, 'chunks', {
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configurable: true,
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writable: true,
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enumerable: false,
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value: chunks,
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});
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Object.defineProperty(IteratorPrototype, 'windows', {
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configurable: true,
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writable: true,
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enumerable: false,
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value: windows,
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});

‎test/index.mjs

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import { test } from 'node:test';
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import * as assert from 'node:assert/strict';
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import '../lib/index.js';
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function* nats(limit) {
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let n = 0;
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while (n < limit) {
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yield n;
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++n;
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}
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}
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test('chunks', async t => {
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assert.deepEqual(
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Array.from(nats(5).chunks()),
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[[0, 1], [2, 3], [4]],
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);
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assert.deepEqual(
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Array.from(nats(5).chunks(1)),
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[[0], [1], [2], [3], [4]],
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);
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assert.deepEqual(
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Array.from(nats(6).chunks(2)),
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[[0, 1], [2, 3], [4, 5]],
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);
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assert.deepEqual(
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Array.from(nats(6).chunks(3)),
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[[0, 1, 2], [3, 4, 5]],
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);
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assert.deepEqual(
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Array.from(nats(6).chunks(100)),
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[[0, 1, 2, 3, 4, 5]],
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);
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assert.deepEqual(
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Array.from(nats(0).chunks(2)),
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[],
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);
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assert.throws(() => {
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nats(1).chunks([2]);
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}, RangeError)
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assert.throws(() => {
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nats(1).chunks(0);
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}, RangeError)
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assert.throws(() => {
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nats(1).chunks(-1);
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}, RangeError)
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assert.throws(() => {
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nats(1).chunks(1.5);
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}, RangeError)
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assert.throws(() => {
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nats(1).chunks(Math.pow(2, 53));
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}, RangeError)
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});
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test('windows', async t => {
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assert.deepEqual(
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Array.from(nats(5).windows()),
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[[0, 1], [1, 2], [2, 3], [3, 4]],
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);
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assert.deepEqual(
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Array.from(nats(5).windows(1)),
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[[0], [1], [2], [3], [4]],
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);
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assert.deepEqual(
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Array.from(nats(6).windows(3)),
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[[0, 1, 2], [1, 2, 3], [2, 3, 4], [3, 4, 5]],
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);
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assert.deepEqual(
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Array.from(nats(6).windows(100)),
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[],
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);
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assert.deepEqual(
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Array.from(nats(0).windows(2)),
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[],
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);
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assert.throws(() => {
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nats(1).windows([2]);
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}, RangeError)
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assert.throws(() => {
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nats(1).windows(0);
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}, RangeError)
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assert.throws(() => {
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nats(1).windows(-1);
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}, RangeError)
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assert.throws(() => {
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nats(1).windows(1.5);
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}, RangeError)
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assert.throws(() => {
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nats(1).windows(Math.pow(2, 53));
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}, RangeError)
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});

‎tsconfig.json

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{
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"compilerOptions": {
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/* Visit https://aka.ms/tsconfig to read more about this file */
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/* Projects */
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"incremental": true, /* Save .tsbuildinfo files to allow for incremental compilation of projects. */
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// "composite": true, /* Enable constraints that allow a TypeScript project to be used with project references. */
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// "tsBuildInfoFile": "./.tsbuildinfo", /* Specify the path to .tsbuildinfo incremental compilation file. */
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// "disableSourceOfProjectReferenceRedirect": true, /* Disable preferring source files instead of declaration files when referencing composite projects. */
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// "disableSolutionSearching": true, /* Opt a project out of multi-project reference checking when editing. */
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// "disableReferencedProjectLoad": true, /* Reduce the number of projects loaded automatically by TypeScript. */
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/* Language and Environment */
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"target": "es2022", /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
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// "lib": [], /* Specify a set of bundled library declaration files that describe the target runtime environment. */
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// "jsx": "preserve", /* Specify what JSX code is generated. */
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// "experimentalDecorators": true, /* Enable experimental support for legacy experimental decorators. */
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// "emitDecoratorMetadata": true, /* Emit design-type metadata for decorated declarations in source files. */
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// "jsxFactory": "", /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h'. */
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// "jsxFragmentFactory": "", /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
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// "jsxImportSource": "", /* Specify module specifier used to import the JSX factory functions when using 'jsx: react-jsx*'. */
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// "reactNamespace": "", /* Specify the object invoked for 'createElement'. This only applies when targeting 'react' JSX emit. */
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// "noLib": true, /* Disable including any library files, including the default lib.d.ts. */
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// "useDefineForClassFields": true, /* Emit ECMAScript-standard-compliant class fields. */
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// "moduleDetection": "auto", /* Control what method is used to detect module-format JS files. */
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/* Modules */
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"module": "es2022", /* Specify what module code is generated. */
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"rootDir": "src", /* Specify the root folder within your source files. */
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// "moduleResolution": "node10", /* Specify how TypeScript looks up a file from a given module specifier. */
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// "baseUrl": "./", /* Specify the base directory to resolve non-relative module names. */
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// "paths": {}, /* Specify a set of entries that re-map imports to additional lookup locations. */
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// "rootDirs": [], /* Allow multiple folders to be treated as one when resolving modules. */
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// "typeRoots": [], /* Specify multiple folders that act like './node_modules/@types'. */
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// "types": [], /* Specify type package names to be included without being referenced in a source file. */
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// "allowUmdGlobalAccess": true, /* Allow accessing UMD globals from modules. */
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// "moduleSuffixes": [], /* List of file name suffixes to search when resolving a module. */
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// "allowImportingTsExtensions": true, /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution bundler' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
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// "resolvePackageJsonExports": true, /* Use the package.json 'exports' field when resolving package imports. */
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// "resolvePackageJsonImports": true, /* Use the package.json 'imports' field when resolving imports. */
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// "customConditions": [], /* Conditions to set in addition to the resolver-specific defaults when resolving imports. */
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// "resolveJsonModule": true, /* Enable importing .json files. */
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// "allowArbitraryExtensions": true, /* Enable importing files with any extension, provided a declaration file is present. */
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// "noResolve": true, /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
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/* JavaScript Support */
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// "allowJs": true, /* Allow JavaScript files to be a part of your program. Use the 'checkJS' option to get errors from these files. */
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// "checkJs": true, /* Enable error reporting in type-checked JavaScript files. */
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// "maxNodeModuleJsDepth": 1, /* Specify the maximum folder depth used for checking JavaScript files from 'node_modules'. Only applicable with 'allowJs'. */
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/* Emit */
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"declaration": true, /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
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// "declarationMap": true, /* Create sourcemaps for d.ts files. */
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// "emitDeclarationOnly": true, /* Only output d.ts files and not JavaScript files. */
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// "sourceMap": true, /* Create source map files for emitted JavaScript files. */
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"inlineSourceMap": true, /* Include sourcemap files inside the emitted JavaScript. */
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// "outFile": "./", /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
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"outDir": "lib", /* Specify an output folder for all emitted files. */
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"removeComments": true, /* Disable emitting comments. */
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// "noEmit": true, /* Disable emitting files from a compilation. */
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// "importHelpers": true, /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
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// "importsNotUsedAsValues": "remove", /* Specify emit/checking behavior for imports that are only used for types. */
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// "downlevelIteration": true, /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
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// "sourceRoot": "", /* Specify the root path for debuggers to find the reference source code. */
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// "mapRoot": "", /* Specify the location where debugger should locate map files instead of generated locations. */
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// "inlineSources": true, /* Include source code in the sourcemaps inside the emitted JavaScript. */
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"emitBOM": false, /* Emit a UTF-8 Byte Order Mark (BOM) in the beginning of output files. */
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"newLine": "lf", /* Set the newline character for emitting files. */
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// "stripInternal": true, /* Disable emitting declarations that have '@internal' in their JSDoc comments. */
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// "noEmitHelpers": true, /* Disable generating custom helper functions like '__extends' in compiled output. */
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// "noEmitOnError": true, /* Disable emitting files if any type checking errors are reported. */
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// "preserveConstEnums": true, /* Disable erasing 'const enum' declarations in generated code. */
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// "declarationDir": "./", /* Specify the output directory for generated declaration files. */
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// "preserveValueImports": true, /* Preserve unused imported values in the JavaScript output that would otherwise be removed. */
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/* Interop Constraints */
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// "isolatedModules": true, /* Ensure that each file can be safely transpiled without relying on other imports. */
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// "verbatimModuleSyntax": true, /* Do not transform or elide any imports or exports not marked as type-only, ensuring they are written in the output file's format based on the 'module' setting. */
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// "allowSyntheticDefaultImports": true, /* Allow 'import x from y' when a module doesn't have a default export. */
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"esModuleInterop": true, /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
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"preserveSymlinks": true, /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */
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"forceConsistentCasingInFileNames": true, /* Ensure that casing is correct in imports. */
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/* Type Checking */
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"strict": true, /* Enable all strict type-checking options. */
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"noImplicitAny": true, /* Enable error reporting for expressions and declarations with an implied 'any' type. */
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"strictNullChecks": true, /* When type checking, take into account 'null' and 'undefined'. */
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"strictFunctionTypes": true, /* When assigning functions, check to ensure parameters and the return values are subtype-compatible. */
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"strictBindCallApply": true, /* Check that the arguments for 'bind', 'call', and 'apply' methods match the original function. */
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"strictPropertyInitialization": true, /* Check for class properties that are declared but not set in the constructor. */
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"noImplicitThis": true, /* Enable error reporting when 'this' is given the type 'any'. */
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"useUnknownInCatchVariables": true, /* Default catch clause variables as 'unknown' instead of 'any'. */
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"alwaysStrict": true, /* Ensure 'use strict' is always emitted. */
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"noUnusedLocals": true, /* Enable error reporting when local variables aren't read. */
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"noUnusedParameters": true, /* Raise an error when a function parameter isn't read. */
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"exactOptionalPropertyTypes": true, /* Interpret optional property types as written, rather than adding 'undefined'. */
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"noImplicitReturns": true, /* Enable error reporting for codepaths that do not explicitly return in a function. */
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"noFallthroughCasesInSwitch": true, /* Enable error reporting for fallthrough cases in switch statements. */
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"noUncheckedIndexedAccess": true, /* Add 'undefined' to a type when accessed using an index. */
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"noImplicitOverride": true, /* Ensure overriding members in derived classes are marked with an override modifier. */
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"noPropertyAccessFromIndexSignature": true, /* Enforces using indexed accessors for keys declared using an indexed type. */
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// "allowUnusedLabels": true, /* Disable error reporting for unused labels. */
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// "allowUnreachableCode": true, /* Disable error reporting for unreachable code. */
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/* Completeness */
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// "skipDefaultLibCheck": true, /* Skip type checking .d.ts files that are included with TypeScript. */
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"skipLibCheck": true /* Skip type checking all .d.ts files. */
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}
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}

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