How can I perform a function only once in a period of time

Question

I wanted to know how to do a single execution, example:

In my application there is a way to schedule charges and they are scheduled per day, then on a certain day X she will be charged.

---

I’m currently doing it this way:

const da = Number(new Intl.DateTimeFormat('pt-br', { day: '2-digit' }).format(new Date(Date.now())));

let arr = [
  { name: "Salário", amount: 150000, day: 5 },
  { name: "Internet", amount: -11590, day: 10 },
  { name: "Teste", amount: 15000, day: 5 },
];

const indexofday = arr.reduce((acc, obj, index) => {
  if (obj.day === da) {
    acc.push(index);
  }
  return acc;
}, []);

const newarr = indexofday.map((item) => Array[item]);

//Função para adicionar essa array em outro local da aplicação. O concat e somente um exemplo!

newarr.forEach((transaction, index) => {
  datastorage.concat(transaction, index);
});

This function is what I am currently using, but when I refresh the page and the day remains the same, it runs this function again! It creates a loop in my application. Is there any way to perform this only once a day?

Answer 1

Following the logic you intend to apply:

• the script must be executed once every 24hs period
• its function checks if the current day is equal to the billing day (monthly)
• if it is equal executes

I believe you should move your code to a function that checks a time indicator and makes the following comparison:

• 1: get if indicator exists, if it does not exist. Create and call the function
• 2: if the indicator exists, check if it is greater than the current period (24hs)
• 3: if the period is longer, sets a new indicator and performs the function
• 4: if the period is shorter, does not perform the function and does not adjust the current indicator

I can’t say it’s the best indication but, use a Timestamp as indicator would allow to make this check in the "front-end".

There are "n" modes of storing this indicator in "front-end", here I am using document.cookie and taking the liberty of modifying the day from its first collection object to the present day so you can see that the cookie is created and the function is called only once ... There will only be called again after 24hs.

NOTE: concealed the exit of console of the snippet below because it runs on a <iframe> and cannot save cookies for security reasons.

// defina um nome mais apropriado
const SuaFunção = function() {
    // millisegundos de 24Hs
    const DayInMilliseconds = (24 * 60 * 60 * 1000)
    // cookie search
    const search = name => {
        return document.cookie.replace(new RegExp("(?:(?:^|.*;)\\s*" + name.replace(/[\-\.\+\*]/g, "\\$&") + "\\s*\\=\\s*([^;]*).*$)|^.*$"), "$1") || false
    }
    // função que retorna a data de expiração do cookie (formato GMT)
    const makeTime = t => {
        if ( typeof t === 'number' ) {
            let d = new Date()
            d.setMilliseconds(d.getMilliseconds() + t * DayInMilliseconds)
            return d.toString()
        }
    }
    //
    const paymentFn = () => {
        const da = Number(new Intl.DateTimeFormat('pt-br', { day: '2-digit' }).format(new Date(Date.now())));

        let arr = [
          { name: "Salário", amount: 150000, day: da },
          { name: "Internet", amount: -11590, day: 10 },
          { name: "Teste", amount: 15000, day: 5 },
        ];

        const indexofday = arr.reduce((acc, obj, index) => {
          if (obj.day === da) {
            acc.push(index);
          }
          return acc;
        }, []);

        const newarr = indexofday.map((item) => Array[item]);

        //Função para adicionar essa array em outro local da aplicação. O concat e somente um exemplo!

        newarr.forEach((transaction, index) => {
          //datastorage.concat(transaction, index);
          console.log(transaction, index)
        });
    }

    // procura seu cookie (exemplo: "payment")
    const PaymentCookie = search('payment'),
        // pega o Timestamp atual
        TSNow = Date.now()
    if ( PaymentCookie ) {
        /*
           verifica se o Timestamp do cookie + um periodo de 24Hs (em millisegundos) é maior que o atual Timestamp
           o que significa que ainda não se passaram 24Hs
         */ 
        if ( Number(PaymentCookie) + DayInMilliseconds > TSNow ) {
            // o Timestamp do cookie ainda não passou de 24Hs
            console.log('Ainda não passaram mais de 24Hs')
            // retorna sem fazer nada, não invoca sua função de cobrança
            return
        }
        // o Timestamp do cookie já passou de 24Hs
        console.log('Já passaram mais de 24Hs')
        // caso a instrução acima não execute (por já ter passado de 24Hs) cria um novo cookie
        document.cookie = `payment=${TSNow}; expires=${makeTime(30)}`
        // executa sua função
        paymentFn()
    } else {
        // primeira execução
        console.log('Não há cookie, vamos criar um')
        // cria novo cookie com o atual Timestamp e executa sua função (expira em 30 dias)
        document.cookie = `payment=${TSNow}; expires=${makeTime(30)}`
        // chama sua função
        paymentFn()
    }
}

// chama a função em qualquer parte do script principal
SuaFunção()

---

Sources:

https://developer.mozilla.org/en-US/docs/Web/API/Document/cookie

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Greater_than

---

Additional reading:

https://hkotsubo.github.io/blog/2019-05-02/o-que-e-timestamp

Convert date from DD/MM/YYYY to YYYY-MM-DD in Javascript