mobx computed always update that computed doesn't work

Question

import {makeAutoObservable} from "mobx";

class Test {
    id = 0
    constructor() {
        makeAutoObservable(this)
    }

    get total() {
        console.log('enss')
        return 2;
    }
}

const store = new Test();
export default store;

call:

import {isComputed, isComputedProp} from "mobx";

console.log(isComputedProp(Test, 'total'),Test.total,Test.total, Test.total, isComputedProp(Test, 'total'))

console output: enss enss enss true 2 2 2 true

the computed did not work and does not serve as a cache. i using mobx 6.6 version in react 18.

Thank you very much for your answer！

Answer 1

This is explained in the docs here

It sometimes confuses people new to MobX, perhaps used to a library like Reselect, that if you create a computed property but don't use it anywhere in a reaction, it is not memoized and appears to be recomputed more often than necessary. For example, if we extended the above example with calling console.log(order.total) twice, after we called stop(), the value would be recomputed twice.

Basically it won't be cached if you use it outside of reactive context.

You can use computed({ keepAlive: true }) option to change this behaviour