merge-descriptors

What is merge-descriptors?

The merge-descriptors npm package is a utility that allows you to copy enumerable properties from one or more source objects to a destination object, optionally defining property descriptors. It is commonly used to mix properties and their descriptors from one object into another, preserving more detailed configuration than a simple object spread or Object.assign.

What are merge-descriptors's main functionalities?

Merge properties with descriptors

This feature allows you to merge properties from the source object to the target object, including their getters and setters. The example shows how a property with a getter is copied to the target object, preserving its behavior.

const mergeDescriptors = require('merge-descriptors');
let target = {};
let source = { get foo() { return 'bar'; } };
mergeDescriptors(target, source);
console.log(target.foo); // Outputs: 'bar'

Merge properties without overwriting

This feature demonstrates how to merge properties without overwriting existing properties in the target object. The example merges a getter for 'foo' from the source into the target, but since 'foo' already exists in the target and the overwrite flag is set to false, the original value is preserved.

const mergeDescriptors = require('merge-descriptors');
let target = { foo: 'initial' };
let source = { get foo() { return 'bar'; } };
mergeDescriptors(target, source, false);
console.log(target.foo); // Outputs: 'initial'

Other packages similar to merge-descriptors

lodash.merge

Lodash's merge function is similar to merge-descriptors but focuses more on deep merging of properties, including arrays and plain objects. Unlike merge-descriptors, lodash.merge does not handle property descriptors, making it less suitable for cases where property getters, setters, or other descriptor specifics are crucial.

object-assign

The object-assign package provides a function to copy values of all enumerable own properties from one or more source objects to a target object. It is similar to Object.assign() and does not copy property descriptors, making merge-descriptors a better choice when descriptors need to be preserved.

README

Merge Descriptors

Merge objects using descriptors.

var thing = {
  get name() {
    return 'jon'
  }
}

var animal = {

}

merge(animal, thing)

animal.name === 'jon'

API

merge(destination, source)

Overwrites destination's descriptors with source's.

License

The MIT License (MIT)

Copyright (c) 2013 Jonathan Ong [e-mail]

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.