local-storage-set-with-fifo.js

class LocalStorageSet {
    constructor(key, fifoMaxEntries = null) {
        this.key = key;
        this.fifoMaxEntries = fifoMaxEntries;
        this.entries = this.load();
    }

    load() {
        const rawValue = window.localStorage.getItem(
            this.key,
        );

        return JSON.parse(rawValue) || [];
    }

    persist() {
        const entriesToPersist = [...this.entries];

        if (this.fifoMaxEntries !== null && entriesToPersist.length > this.fifoMaxEntries) {
            entriesToPersist.shift();
            this.entries = entriesToPersist;
        }

        const serializedEntries = JSON.stringify(
            entriesToPersist,
        );

        window.localStorage.setItem(
            this.key,
            serializedEntries,
        );
    }

    contains(value) {
        return this.entries.includes(value);
    }

    set(value) {
        if (this.contains(value)) {
            return false;
        }

        this.entries.push(value);
        this.persist();

        return true;
    }   
}

const testStorage = new LocalStorageSet(
    'testStorage',
    5,
);

testStorage.set(1);
testStorage.set(2);
testStorage.set(3);
testStorage.set(4);
testStorage.set(5);
testStorage.set(6);
testStorage.set(7);

console.log('testStorage.contains(1)', testStorage.contains(1));
console.log('testStorage.contains(7)', testStorage.contains(7));

console.log(testStorage.entries);