Node.js module to load a configuration file.

configFileReader.js

/*
    Configuration file reader module. Takes an absolute file path and the boolean watch as arguments.
    * filePath is expected to be the path to a JSON file (with the .json extension).
    * watch is optional and defaults to false. If set to true, the config file will be watched by fs and any changes made to it will be automatically reflected on the module instance.

    Returns an object:
    * filePath: The file currently in use.
    * watching: Boolean, indicate if the config file is being monitored for changes.
    * config: Object containg the parsed data of the config file.
    * parseFile(path, watch): Parse a config file. If you specify a new file, set watch to true to start watching it for changes, too. As always, watch defaults to false.
    * startWatching() \
    ------- and --------> Stop or start watching the current file.
    * stopWatching()  /
*/
class configFileReader {
    constructor(filePath, watch = false) {
        const fs = require("fs");
        this.filePath = filePath;
        this._internal = {
            createWatcher: (filePath) => {
                this._internal.fileWatcher = fs.watch(filePath, (eventType, filename) => {
                    if (eventType === "change") {
                        this.parseFile(filename);
                    }
                });
            }
        };

        this.watching = false;
        this.parseFile(this.filePath);
        if (watch) this.startWatching();
    }
    parseFile(path, watch = false) {
        if (!fs.existsSync(path)) throw("Configuration file not found");
        if (path !== this.filePath && this.watching) this.stopWatching();

        this.config = require(path);

        if (path !== this.filePath) {
            this.filePath = path;
            if (watch) this.startWatching();
        }
    }
    startWatching() {
        if (this.watching) throw("Already watching");
        this._internal.createWatcher(this.filePath);
        this.watching = true;
    }
    stopWatching() {
        if (!this.watching) throw("Not watching anything");

        this._internal.fileWatcher.close();

        this.watching = false;
    }
}

module.exports = configFileReader;