Deep Equality Checking

For simple deep equality, JSON.stringify comparison works for many cases: JSON.stringify(a) === JSON.stringify(b). This is naive because key order affects the string. For production use, lodash.isEqual provides robust deep equality with correct handling of circular references and special types.

Structural Diff for Debugging

Knowing that two objects differ is often less useful than knowing how they differ. Deep-diff and similar libraries produce a structured description of every added, removed, modified, and moved value between two objects — invaluable for debugging API response changes.

Ordered vs Unordered Comparison

Array comparison must specify whether order matters. [1, 2, 3] and [3, 1, 2] are different if the array is an ordered sequence, but equivalent if it represents a set. Object key comparison is always unordered by specification.

Schema Drift Detection

When an API you consume changes its response shape, the change may be subtle. JSON Schema validation on API responses in development detects these changes immediately as validation errors rather than silent runtime failures.

Key Takeaway

Deep JSON comparison requires purpose-built tools, not primitive operators. Use lodash.isEqual for equality checks, deep-diff for structural comparison, and JSON Schema validation to detect breaking API changes.