One-level options with default values and validation

Utility function to merge simple one-level options with default values and perform validation.

Benefits over Object.assign are:

• exclude of undefined values (useful for conditional options):

  const defaults = {foo: 'bar'};
  const options = {foo: undefined};
  
  Object.assign({}, defaults, options); // -> {foo: undefined}
  // vs
  flatOptions(options, defaults); // -> {foo: 'bar'}

• validation of options keys:

  const defaults = {foo: 'bar'};
  const options = {unknown: 'baz'};
  
  Object.assign({}, defaults, options); // -> {foo: 'bar', unknown: 'baz'}
  // vs
  flatOptions(options, defaults); // -> throws error "Unknown option"!

Benefits over existing defaults, lodash.defaults and object.defaults are:

• auto-validation of options keys
• zero dependencies

Note that this package is only for one-level options, for nested ones please use alternative packages

npm install --save flat-options

import flatOptions from 'flat-options';

const defaults = {
  a: 1,
  b: false
};

class Foo {
  constructor(options) {
    this._options = flatOptions(options, defaults);
  }
}

const foo = new Foo({a: 2}); // foo._options will be {a: 2, b: false} 

MIT @ Vitaliy Potapov