Improved deep equality testing for [node](http://nodejs.org) and the browser.
What is Deep-Eql?
Deep Eql is a module which you can use to determine if two objects are "deeply" equal - that is, rather than having referential equality (a === b
), this module checks an object's keys recursively, until it finds primitives to check for referential equality. For more on equality in JavaScript, read the comparison operators article on mdn.
As an example, take the following:
1 === 1
1 == '1'
{ a: 1 } !== { a: 1 }
{ a: 1 } != { a: 1 }
var deepEql = require("deep-eql");
deepEql({ a: 1 }, { a: 1 }) === true
Installation
Node.js
deep-eql
is available on npm.
$ npm install deep-eql
Usage
The primary export of deep-eql
is function that can be given two objects to compare. It will always return a boolean which can be used to determine if two objects are deeply equal.
Rules
- Strict equality for non-traversable nodes according to
Object.is
:
eql(NaN, NaN).should.be.true;
eql(-0, +0).should.be.false;
- All own and inherited enumerable properties are considered:
eql(Object.create({ foo: { a: 1 } }), Object.create({ foo: { a: 1 } })).should.be.true;
eql(Object.create({ foo: { a: 1 } }), Object.create({ foo: { a: 2 } })).should.be.false;
- Arguments are not Arrays:
eql([], arguments).should.be.false;
eql([], Array.prototype.slice.call(arguments)).should.be.true;
- Error objects are compared by reference (see https://github.com/chaijs/chai/issues/608):
eql(new Error('msg'), new Error('msg')).should.be.false;
var err = new Error('msg'); eql(err, err).should.be.true;