ndjson-to-json-stream.js

import * as fs from "fs";
import split from "split2";

export interface ndjsonToJsonTextOption extends split.Options {
}

export function ndjsonToJsonText(ndjsonFileName: string, options: ndjsonToJsonTextOption = {}) {
    function appendComma(line: string) {
        return line + ",";
    }
    return new Promise((resolve, reject) => {
        const fileStream = fs.createReadStream(ndjsonFileName);
        const list: string[] = [];
        fileStream
            .pipe(split(appendComma, options))
            .on("data", function(obj) {
                list.push(obj.toString());
            })
            .on("error", (error: Error) => {
                reject(error);
            })
            .on("end", () => {
                fileStream.close();
                const text = list.join("");
                // trim last ,
                const jsonText = `[${text.substr(0, text.length - 1)}]`;
                resolve(jsonText);
            });
    });