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Resolve an options object based on configuration.


// This example assumes a Vinyl file 
var createResolver = require('resolve-options');
var config = {
  cwd: {
    type: 'string',
    default: process.cwd
  sourcemaps: {
    type: 'boolean',
    default: false
  since: {
    type: ['date', 'number']
  read: {
    type: 'boolean'
var options = {
  sourcemaps: true,
  read: function(file) {
    return (file.extname !== '.mp4');
var resolver = createResolver(config, options);
var cwd = resolver.resolve('cwd', file);
// cwd === process.cwd() 
var sourcemaps = resolver.resolve('sourcemaps', file);
// sourcemaps === true 
var read = resolver.resolve('read', file);
// Given .mp4, read === false 
// Given .txt, read === true 


createResolver([config,] [options])

Takes a config object that describes the options to accept/resolve and an options object (usually passed by a user) to resolve against the config. Returns a resolver that contains a resolve method for realtime resolution of options.

The config object takes the following structure:

config {
  [optionKey] {
    type // string, array or function
    default // any value or function

Each option is represented by its optionKey in the config object. It must be an object with a type property.

The type property must be a string, array or function which will be passed to the value-or-function module (functions will be bound to the resolver to allow for dependent options).

A default property may also be specified as a fallback if the option isn't available or is invalid. The default value can be any value or a function (functions will be bound to the resolver to allow for dependent defaults). Note: default values are not type-validated by the value-or-function module.

resolver.resolve(optionKey, [...arguments])

Takes an optionKey string and any number of arguments to apply if an option is a function. Returns the resolved value for the optionKey.