What is deep equality in JavaScript?

What is deep equality in JavaScript?

Deep equality in JavaScript refers to comparing two objects or arrays to check if they are equivalent in structure and value, including nested properties.

How does deep equality differ from shallow equality?

Shallow equality checks if two references point to the same object or if their first-level properties are equal, while deep equality checks all nested properties.

Can you show me an example of how to implement deep equality?

Sure! You can implement deep equality using recursion to compare each property of the objects. Here's a simple function:

function deepEqual(obj1, obj2) {
    if (obj1 === obj2) return true;
    if (obj1 == null || obj2 == null) return false;
    if (typeof obj1 !== 'object' || typeof obj2 !== 'object') return false;

    const keys1 = Object.keys(obj1);
    const keys2 = Object.keys(obj2);
    if (keys1.length !== keys2.length) return false;

    for (let key of keys1) {
        if (!keys2.includes(key) || !deepEqual(obj1[key], obj2[key])) {
            return false;
        }
    }
    return true;
}

This function checks if two objects are deeply equal.

Are there any libraries that can help with deep equality checks?

Yes, libraries like Lodash provide a _.isEqual function that can perform deep equality checks efficiently.