immer-patches.js

var immer = require("immer");
var produce = immer.produce;

var patches = [];
var state0 = { a: 1 };
var state1 = produce(
  state0,
  function (draft) {
    draft.b = 9;
  },
  function (p) {
    patches.push(...p);
  }
);
var state2 = produce(
  state1,
  function (draft) {
    draft.a = 3;
  },
  function (p) {
    patches.push(...p);
  }
);
var state3 = produce(
  state2,
  function (draft) {
    draft.b = 99;
  },
  function (p) {
    patches.push(...p);
  }
);
var state4 = produce(
  state3,
  function (draft) {
    draft.a = 5;
  },
  function (p) {
    patches.push(...p);
  }
);

console.log(patches);
//Array (4 items)
//0: Object {op: "add", path: , value: 9}
//1: Object {op: "replace", path: , value: 3}
//2: Object {op: "replace", path: , value: 99}
//3: Object {op: "replace", path: , value: 5}

var applyPatches = immer.applyPatches;

produce(
  state0,
  function (draft) {
    applyPatches(draft, patches);
  },
  function (p) {
    patches = p;
  }
);

console.log(patches);
//Array (2 items)
//0: Object {op: "add", path: , value: 99}
//1: Object {op: "replace", path: , value: 5}