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Mirror: A Node.js fetch shim using built-in Request, Response, and Headers (but without native fetch)
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2.0 kB · 72 lines
TypeScript
at main
12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273import { PassThrough, Transform, TransformCallback } from 'node:stream';import * as zlib from 'node:zlib';
/** @see https://www.rfc-editor.org/rfc/rfc9112.html#section-7.2 */type Encoding = 'gzip' | 'x-gzip' | 'deflate' | 'x-deflate' | 'br' | {};
/** @see https://github.com/nodejs/undici/pull/2650 */class InflateStream extends Transform { _opts?: zlib.ZlibOptions; _inflate?: Transform;
constructor(opts?: zlib.ZlibOptions) { super(); this._opts = opts; }
_transform( chunk: Buffer, encoding: BufferEncoding, callback: TransformCallback ) { if (!this._inflate) { if (chunk.length === 0) { callback(); return; } this._inflate = (chunk[0] & 0x0f) === 0x08 ? zlib.createInflate(this._opts) : zlib.createInflateRaw(this._opts); this._inflate.on('data', this.push.bind(this)); this._inflate.on('end', () => this.push(null)); this._inflate.on('error', err => this.destroy(err)); } this._inflate.write(chunk, encoding, callback); }
_final(callback: TransformCallback) { if (this._inflate) { this._inflate.once('finish', callback); this._inflate.end(); this._inflate = undefined; } else { callback(); } }}
export const createContentDecoder = (encoding: Encoding | {}) => { // See: https://github.com/nodejs/undici/blob/008187b/lib/web/fetch/index.js#L2138-L2160 switch (encoding) { case 'br': return zlib.createBrotliDecompress({ flush: zlib.constants.BROTLI_OPERATION_FLUSH, finishFlush: zlib.constants.BROTLI_OPERATION_FLUSH, }); case 'gzip': case 'x-gzip': return zlib.createGunzip({ flush: zlib.constants.Z_SYNC_FLUSH, finishFlush: zlib.constants.Z_SYNC_FLUSH, }); case 'deflate': case 'x-deflate': return new InflateStream({ flush: zlib.constants.Z_SYNC_FLUSH, finishFlush: zlib.constants.Z_SYNC_FLUSH, }); default: return new PassThrough(); }};