Auto freezing

egghead.io lesson 7: Immer automatically freezes data

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Immer automatically freezes any state trees that are modified using produce. This protects against accidental modifications of the state tree outside of a producer. In most cases this provides the most optimal behavior, but setAutoFreeze(true / false) can be used to explicitly turn this feature on or off.

Immer will never freeze (the contents of) non-enumerable, non-own or symbolic properties, unless their content was drafted.

⚠️ Immer freezes everything recursively, for large data objects that won't be changed in the future this might be over-kill, in that case it can be more efficient to shallowly pre-freeze data using the freeze utility.⚠️

⚠️ If auto freezing is enabled, recipes are not entirely side-effect free: Any plain object or array that ends up in the produced result, will be frozen, even when these objects were not frozen before the start of the producer! ⚠️