JarCastingmerge-options 
Merge Option Objects
merge-options considers plain objects as Option Objects, everything else as Option Values.
Install
$ npm install --save merge-options
Usage
const mergeOptions = require('merge-options');
mergeOptions({foo: 0}, {bar: 1}, {baz: 2}, {bar: 3})
//=> {foo: 0, bar: 3, baz: 2}
mergeOptions({nested: {unicorns: 'none'}}, {nested: {unicorns: 'many'}})
//=> {nested: {unicorns: 'many'}}
mergeOptions({[Symbol.for('key')]: 0}, {[Symbol.for('key')]: 42})
//=> {Symbol(key): 42}
Usage with custom config
const mergeOptions = require('merge-options').bind({ignoreUndefined: true});
mergeOptions({foo: 'bar'}, {foo: undefined})
//=> {foo: 'bar'}
API
mergeOptions(option1, ...options)
mergeOptions.call(config, option1, ...options)
mergeOptions.apply(config, [option1, ...options])
mergeOptions recursively merges one or more Option Objects into a new one and returns that. The options are merged in order, thus Option Values of additional options take precedence over previous ones.
The merging does not alter the passed option arguments, taking roughly the following steps:
- recursively cloning[1] Option Objects and arrays until reaching Option Values
- copying[1] references to Option Values to the result object
const defaultOpts = {
fn: () => false, // functions are Option Values
promise: Promise.reject(new Error()), // all non-plain objects are Option Values
array: ['foo'], // arrays are Option Values
nested: {unicorns: 'none'} // {…} is plain, therefore an Option Object
};
const opts = {
fn: () => true, // [1]
promise: Promise.resolve('bar'), // [2]
array: ['baz'], // [3]
nested: {unicorns: 'many'} // [4]
};
mergeOptions(defaultOpts, opts)
//=>
{
fn: [Function], // === [1]
promise: Promise { 'bar' }, // === [2]
array: ['baz'], // !== [3] (arrays are cloned)
nested: {unicorns: 'many'} // !== [4] (Option Objects are cloned)
}
config
Type: object
config.concatArrays
Type: boolean
Default: false
Concatenate arrays:
mergeOptions({src: ['src/**']}, {src: ['test/**']})
//=> {src: ['test/**']}
// Via call
mergeOptions.call({concatArrays: true}, {src: ['src/**']}, {src: ['test/**']})
//=> {src: ['src/**', 'test/**']}
// Via apply
mergeOptions.apply({concatArrays: true}, [{src: ['src/**']}, {src: ['test/**']}])
//=> {src: ['src/**', 'test/**']}
config.ignoreUndefined
Type: boolean
Default: false
Ignore undefined values:
mergeOptions({foo: 'bar'}, {foo: undefined})
//=> {foo: undefined}
// Via call
mergeOptions.call({ignoreUndefined: true}, {foo: 'bar'}, {foo: undefined})
//=> {foo: 'bar'}
// Via apply
mergeOptions.apply({ignoreUndefined: true}, [{foo: 'bar'}, {foo: undefined}])
//=> {foo: 'bar'}
Related
- See object-assign if you need a ES2015 Object.assign() ponyfill
- See deep-assign if you need to do Object.assign() recursively
Notes
- copying and cloning take only enumerable own properties into account
License
MIT © Michael Mayer