@cley_faye/loadconfig

Load configuration by looking into multiple places, updating values with each lookup:

• default values
• from a specific section in package.json
• from a json file
• from a js file
• from command line flags

Configuration is very basic, and mostly handle strings, numbers, bool and array of those. Array values defined in later configuration source overrides completely values from previous sources. This mean that an array value set in a json file would be completely erased by a value set in a js file or on command line.

Usage

Where you need your configuration, call the function exported by the library.

import loadConfig from "@cley_faye/loadconfig";

loadConfig(
  {
    options,
    configName,
  },
).then(config => {});

The result is cached by default; that is because CLI arguments are removed from argv, so subsequent calls could return a different value than the first call.

Settings

Configuring options

Each value can be either a string, a number, a boolean, or an array of these. For array values, it means that the command line will accept multiple occurrence of the same argument. The options argument is an object where keys are configuration options names and values are objects that have the following properties:

• cliName: optional name for reading from the command line (default to kebab case of the option name)
• multiple: set to true to change the option type to be an array of values
• type: expected value type. Only used for reading from CLI. Can be string, number or boolean. A special type object can be used; it will pass the content of the json/javascript config as-is, and cannot be used for CLI.
• defaultValue: an optional default value

Naming the config source

The configName argument is the name to use when looking for configuration in package.json and in external files. It is used to find a property by that name in package.json, and for files names .<configName>.js and .<configName>.json.

It is possible to disable prefixing the config files by a dot (.) by adding the noDotFile property, set to true. It is also possible to skip some data source by setting the disableSource property.

From command line

Options can be read from command line. If an argument match, it is removed from the list of arguments. If the same argument is matched multiple time, only the latest one is kept, except for properties that are arrays, in which case each value is concatenated to the array. It is possible to remove a value using --no-<arg name>, except for booleans where it would set them to false.