vue-reactivity-in-node.js

const { computed, ref, effect } = require('@vue/reactivity')

let users = ref([])
let onlineUsers = computed(() => {
    return users.value.filter((user) => user.status === 'online')
})

effect(() => {
    console.log('# of online users changed', onlineUsers.value.length)
})

setInterval(() => {
    const status = Math.random() > 0.5 ? 'online' : 'offline'
    console.log(`adding ${status} user`)
    users.value.push({ status })
}, 1000)