deep-eql is not optimized for performance, especially with large or deeply nested structures. Its focus on accuracy and handling edge cases can lead to slower comparisons in some scenarios, making it less suitable for performance-critical applications.

deep-equal offers reasonable performance for most deep equality checks, but it does not include optimizations for specific data types. Its simplicity means that it does not have the overhead of complex algorithms, but it may not be the fastest option for large or nested structures.

fast-equals is designed for high performance, particularly when comparing arrays and objects. It uses optimized algorithms to reduce the time complexity of comparisons, making it one of the fastest libraries for deep equality checks, especially in performance-sensitive applications.

deep-eql handles circular references gracefully, allowing for comparisons of objects that reference themselves or each other. This is particularly useful for comparing complex data structures like trees or graphs, where circular references can occur.

deep-equal does not handle circular references by default, which can lead to infinite loops and stack overflow errors when comparing such structures. It is important to ensure that the data being compared is free of circular references to avoid issues.

fast-equals does not explicitly handle circular references, but its performance characteristics make it less prone to issues with them. However, like deep-equal, it is recommended to avoid comparing structures with circular references to prevent potential problems.

deep-eql allows for customization through the use of equality functions, which can be provided as options to handle specific types of comparisons. This flexibility makes it suitable for scenarios where default equality checks are not sufficient.

deep-equal does not provide much customization beyond the default deep equality algorithm. It is designed to be simple and straightforward, with little room for modification or extension.

fast-equals supports customization by allowing users to provide their own comparison functions for specific types. This feature adds flexibility while maintaining the library's focus on performance.

Deep Comparison with deep-eql

const deepEql = require('deep-eql');

const obj1 = { a: 1, b: { c: 2 } };
const obj2 = { a: 1, b: { c: 2 } };
const obj3 = { a: 1, b: { c: 3 } };

console.log(deepEql(obj1, obj2)); // true
console.log(deepEql(obj1, obj3)); // false

Deep Comparison with deep-equal

const deepEqual = require('deep-equal');

const obj1 = { a: 1, b: { c: 2 } };
const obj2 = { a: 1, b: { c: 2 } };
const obj3 = { a: 1, b: { c: 3 } };

console.log(deepEqual(obj1, obj2)); // true
console.log(deepEqual(obj1, obj3)); // false

Fast Deep Comparison with fast-equals

const { equals } = require('fast-equals');

const obj1 = { a: 1, b: [2, 3] };
const obj2 = { a: 1, b: [2, 3] };
const obj3 = { a: 1, b: [2, 4] };

console.log(equals(obj1, obj2)); // true
console.log(equals(obj1, obj3)); // false