Hard Object References: Stable Object References for Mutable Application State

In JavaScript and TypeScript, object references are often treated as disposable. An object is created, assigned to a variable, passed around, replaced, copied, spread, cloned, and eventually discarded. That is normal language behavior, but in larger mutable systems it creates a specific class of bugs: stale aliases. A stale alias appears when one part of the program still holds a reference to an old object while another part has already replaced that object with a new one. The old reference is still valid JavaScript, but it no longer points to current data. Hard Object References is a discipline for avoiding that class of bugs. The idea is simple: Object and array references should be stable. Do not replace them as a normal update mechanism. Copy data into existing objects instead. This rule is useful for application state, but it is not limited to global stores. It applies to ordinary variables, local component state, nested fields, arrays, drafts, snapshots, runtime models, and temporary objects. The broader principle is: Replace primitive values. Do not replace object and array references. The First Rule: const for Objects and Arrays The first level is variable bindings. If a variable holds an object or array, it should normally be declared with const : const user = { /* ... */ }; const items = [ /* ... */ ]; not: let user = { /* ... */ }; let items = [ /* ... */ ]; The point is not that the object becomes immutable. It does not. This is still possible: user . name = ' Alex ' ; items . push ( nextItem ); The point is that the variable should not be rebound to a different object: user = nextUser ; items = nextItems ; That replacement changes which object the variable points to. Any other code that still holds the old reference now points to obsolete data. So the first rule is: Use const for object and array references. Mutate or copy data into the object. Do not rebind the reference. This rule also applies to temporary objects. A temporary object may be short-live