object diff

Get the minimal patch to extend objectA with to transform it into objectB

[![npm version][npm-image]][npm-url]

Consider an object retrieved from a server:

{
	name: 'Peter',
	age: 26,
	height: 187,
}

Now the user changes stuff using some frontend (e.g. a HTML form) and ends with:

{
	name: 'Peter',
	age: 27,
	height: 186,
}

When he hits save, you only want to send off the changed parts to the servers, to save bits (because you're indeed a programmer), but also to avoid any unnecessary "merge conflicts" at the server.

Imagine two users changing the same object; if they did not change the exact same keys of the object, the last user won't erase the first user's changes - in a lot of cases, that's the expected behavior.

Install

npm install object-diff

Usage

var diff = require('object-diff');

var a = {
	speed: 4,
	power: 54,
	height: undefined,
	level: 1,
};

var b = {
	speed: 4,			// unchanged
	power: 22,			// changed
	level: undefined,	// changed
	weight: 10,			// added
};

diff(a, b);
/*
{
	power: 22,
	level: undefined,
	weight: 10,
}
*/


// using a custom equality function

var past = '2016-04-24T10:39:23.419Z';

diff.custom({
	equal: dateAwareComparator,
}, {
	then: new Date(past),
}, {
	then: new Date(past),
});
/*
{}
*/

function dateAwareComparator( a, b ){
	if (a instanceof Date && b instanceof Date)
		return a.getTime() === b.getTime();

	return a === b;
}

License

MIT © src.agency / Thomas Jensen [npm-image]: https://img.shields.io/npm/v/object-diff.svg?style=flat [npm-url]: https://npmjs.org/package/object-diff