Mastering Immutable.js

Detecting changes before transformations

With Immutable.js collections, the idea is to detect any changes before any transformations and side-effects are run. You could, for example, detect changes after transformations but before side-effects:

const myList = List.of(1, 2, 3);const mySideEffect = (list) => {  const transformed = list    .map(v => v * v);  if (!transformed.equals(mySideEffect.prev)) {    mySideEffect.prev = transformed;    transformed.forEach(      v => console.log('transformed', v)    );  }};mySideEffect(myList);// -> transformed 1// -> transformed 4// -> transformed 9mySideEffect(myList.set(0, 1));mySideEffect(myList.push(4));// -> transformed 1// -> transformed 4// -> transformed 9// -> transformed 16mySideEffect(myList.push(4));

The mySideEffect() ...