How can I use setInterval and clearInterval in two different function?-CodePudding

What am I missing here? I can call myInterval function, but I can't stop it with clearInterval.

const getData = () => {
db.transaction((tx) => {
  tx.executeSql(
    "SELECT * FROM itinerary_details",
    [],
    (tx, results) => {
      var data = [];
      for (let i = 0; i < results.rows.length;   i)
        data.push(results.rows.item(i));
      console.log(data) 
    }
  )
})
}

So I am trying to have 2 buttons with 2 different function that I can call:

to start:

const myInterval = () => {
   setInterval(getData, 5000)
}

to end the setInterval:

const stopData = () => {
   clearInterval(myInterval)
   console.log("STOPED")
}

I can see the console.log, but not calling the function myInterval

Please help.

CodePudding user response：

You need to store the interval ID somwhere and when clearing, you need this one.

let intervalID = null; // global

const
    startData = () => {
        if (intervalID !== null) return;
        intervalID = setInterval(getData, 5000);
    },
    stopData = () => {
        if (intervalID === null) return;
        clearInterval(intervalID);
        intervalID = null;
        console.log("STOPED");
    },
    getData = () => console.log(new Date().toISOString()   ': getData');

document.getElementById('start').addEventListener('click', startData);
document.getElementById('stop').addEventListener('click', stopData);

<button id="start">Start</button> <button id="stop">Stop</button>

CodePudding user response：

Change it to

const myInterval = setInterval(getData, 5000);

From the https://developer.mozilla.org/en-US/docs/Web/API/setInterval:

The returned ... is a numeric, non-zero value which identifies the timer created by the call to setInterval(); this value can be passed to clearInterval() to cancel the interval.

So, in your case, the returned value is not what is returned from setInterval itself, yet a different function.

Note: the answer is on assumption you are using myInterval in the same scope where you set and clear it.