Create a new Config Object:

const cfg = new Config("./path/to/file.json", {
    createOnNoEntry: true,
    autoReload: true
});

Available options are:

Note: When no schema is provided, it will search for a file prefixed by .schema with the same config name.

Will trigger and read the local configuration (on disk). A default payload value can be provided in case the file doesn't exist !

const { strictEqual } = require("assert");

const cfg = new Config("./path/to/file.json");
strictEqual(cfg.configHasBeenRead, false); // true
await cfg.read();
strictEqual(cfg.configHasBeenRead, true); // true

Retriggering the method will made an hot-reload of all properties. For a cold reload you will have to close the configuration before.

Warning When the file doesn't exist, the configuration is written at the next loop iteration (with lazyWriteOnDisk).

Setup hot reload (with a file watcher). This method is automatically triggered if the Configuration has been created with the option autoReload set to true.

We use the package node-watch to achieve the hot reload.

Get a value from a key (fieldPath). For example, let take a json payload with a root foo field.

const cfg = new Config("./path/to/file.json");
await cfg.read();
const fooValue = cfg.get("foo");

Under the hood the method work with lodash.get function.

If the retrieved value is a JavaScript object, you can limit the depth by setting depth option.

Set a given field in the configuration.

const cfg = new Config("./config.json", {
    createOnNoEntry: true
});

await cfg.read({ foo: "bar" });
cfg.set("foo", "hello world!");
await cfg.writeOnDisk();

Under the hood the method work with lodash.set function.

Observe a given configuration key with an Observable Like object!

const { writeFile } = require("fs").promises;
const cfg = new Config("./config.json", {
    autoReload: true,
    createOnNoEntry: true
});
await cfg.read({ foo: "bar" });

// Observe initial and next value(s) of foo
cfg.observableOf("foo").subscribe(console.log);

// Re-write local config file
const newPayload = { foo: "world" };
await writeFile("./config.json", JSON.stringify(newPayload, null, 4));

Write the configuration on the disk.

Write the configuration on the disk (only at the next event-loop iteration). Use the event configWritten to known when the configuration will be written.

const cfg = new Config("./config.json", {
    createOnNoEntry: true
});
await cfg.read();
cfg.once("configWritten", () => {
    console.log("Configuration written!");
});
cfg.lazyWriteOnDisk();

Close (and write on disk) the configuration (it will close the watcher and complete/clean all active observers subscribers).

The STRINGIFY_SPACE property allow you to redine the espace used internaly for JSON.stringify method. The default value is 4.

The DEFAULTSchema property allow you to redefine the default schema that should be applied if no schema is provided when constructor is triggered!

The default value is the following Object:

{
    title: "CONFIG",
    additionalProperties: true
}

The DEFAULT_EXTENSION property allow you to redefine the default extension when there is no extension detected in the constructor filePath. The extension can be either .json or .toml.