batchjs/dist/esm/streams/classes/CountStream.js

Batch processing framework for NodeJS

import { SingleObjectDuplex } from "../interfaces/_index";
/**
 * @class
 * Class that allows you to count the number of chunks in a stream.
 * @extends SingleObjectDuplex
 * @template T
 * @example
 * ```typescript
 * const stream:CountStream<string> = new CountStream({
 *     objectMode: true,
 * });
 *
 * stream.write("data1");
 * stream.write("data2");
 * stream.write("data3");
 * stream.end();
 *
 * stream.on("data", (chunk: number) => {
 *     console.log(``Received chunks: ${chunk}```);
 * });
 * ```
 * ```shell
 * >> Received chunks: 3
 * ```
 */
export class CountStream extends SingleObjectDuplex {
    result = 0;
    /**
     * @constructor
     * @param {ObjectDuplexOptions} options - The options for the GroupBy.
     */
    constructor(options) {
        super(options, () => false);
    }
    /**
     * Writes a chunk of data to the stream, groups it according to a specified function,
     * and executes the callback.
     *
     * @param {T} chunk - The data chunk to write to the stream.
     * @param {BufferEncoding} encoding - The encoding of the data.
     * @param {TransformCallback} callback - The callback function to be executed after writing the data.
     * @return {void}
     */
    _write(chunk, encoding, callback) {
        this.result++;
        callback();
    }
}