bob-gray/serviceberry-json

"use strict";

const {Transform} = require("stream");

class JsonSerializerStream extends Transform {
    #previous;

    constructor () {
        super({
            writableObjectMode: true,
            allowHalfOpen: false
        });

        this.push("[\n");
    }

    _transform (chunk, encoding, done) {
        this._pump(",\n");
        this.#previous = chunk;
        done();
    }

    _flush (done) {
        this._pump("\n");
        this.push("]");
        this.#previous = null;
        done();
    }

    _pump (delimiter) {
        if (this.#previous) {
            this.push(JSON.stringify(this.#previous) + delimiter);
        }
    }
}

module.exports = JsonSerializerStream;