How to use the applyPatches function from immer

immer.applyPatches is a function in the Immer library that applies a set of patches to a given state and returns a new state.

How does immer.applyPatches work?

immer.applyPatches is a function in the Immer library that applies a set of patches to a given state and returns a new state. The function takes two arguments: the first argument is the current state object that you want to modify, and the second argument is an array of patches that you want to apply to the state object. Each patch in the array is an object with several properties that describe the change that needs to be made to the state object. The immer.applyPatches function applies each patch in turn to the state object, producing a new state object that reflects the changes described by the patches. Internally, immer.applyPatches uses the same "copy-on-write" mechanism as the rest of the Immer library. When a patch is applied, Immer creates a new copy of the state object and modifies that copy instead of modifying the original object. This allows Immer to track changes to the state object and undo them if necessary, without modifying the original object. immer.applyPatches is useful in situations where you need to make multiple changes to a state object in a controlled and reversible manner, such as when working with complex state in a Redux store.

Ai Example

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const { applyPatches } = require("immer");

// Define the original state object
const state = {
  name: "John",
  age: 30,
  address: {
    street: "123 Main St",
    city: "Anytown",
    state: "CA",
  },
};

// Define a set of patches to apply to the state object
const patches = [
  { op: "replace", path: "/name", value: "Jane" },
  { op: "add", path: "/phone", value: "555-1234" },
  { op: "replace", path: "/address/city", value: "Newtown" },
];

// Apply the patches to the state object
const newState = applyPatches(state, patches);

console.log(newState);

In this example, we start by defining an original state object that contains a name, age, and address. We then define an array of patches that describe changes we want to make to the state object. The first patch replaces the name property with a new value, the second patch adds a new phone property to the state object, and the third patch replaces the city property of the address object with a new value. We then use immer.applyPatches to apply the patches to the original state object and produce a new state object that reflects the changes described by the patches. Finally, we output the new state object to the console using console.log. The output of this example will be a new state object that is identical to the original state object, except that the name property has been changed to "Jane", a new phone property has been added, and the city property of the address object has been changed to "Newtown".