getConfig()

import { getConfig } from '@dr.pogodin/react-utils';

type ConfigT = Record<string, unknown>;

// There are two signature overloads provided:
function getConfig<T extends ConfigT>(sync?: boolean): T | Promise<T>;

function getConfig<T extends ConfigT>(sync: true): T;

The getConfig() function returns the isomorphic (available both at the server- and the client-side) application configuration object, or a promise that resovles to that object.

At the server side this configuration object is provided by the node-config library, it is always available synchronously (i.e. this function always returns the object, rather than its promise), and it essentially behaves the same as the direct node-config library import.

For the client side this configuration object is made available via injection into HTML template during the server-side rendering. This injection is decoded during the client-side application initialization by the client() function, and is returned from getConfig() as the configuration object. For all client-side calls to getConfig() inside React components it is guaranteed that the configuration object is returned directly (because client() waits for the injection decoding prior to start the rendering & hydration of React tree); however calls to getConfig() elsewhere in the code, if done prior to the injection having been processed, will result in getConfig() returning a promise that resolves to the injected configuration object, once it is available.

Also, prior to the configuration object injection, the server side strips from the injected config the SECRET segment, if present, thus providing a configuration segment where server-side only secret can be stored

Example

/config/default.json

module.exports = {
  // These configuration entries are available both client- and server-side:
  SAMPLE_KEY: 'sample value',
  SAMPLE_SEGMENT: {
    KEY_1: 'value 1',
    KEY_2: 'value 2',
  },

  // This entire segment is only available at the server-side,
  // and it is automatically stripped away from the configuration object
  // injected into the client-side.
  SECRET: {
    SERVER_SIDE_SECRET: 'secret value',
  },
}

Also, our library may add some extra fields to the config loaded by node-config; for example it automatically adds CSRF token field to the configuration injected into the client-side code.

Generic Parameters

• T — The type of returned config object, it should extends ConfigT, defined as Record<string, unknown>.

Arguments

• sync — boolean — Optional. If true, the function returns config object synchronously, if it is possible at the moment of the call, or it throws an error otherwise.

Result

This function returns either the configuration object, or a promise that resolves to that object, one it becomes available (see details in the function description above).