Typescript - Multiple setInterval calls

Question

I have a function in which I'd like several setInterval calls, however the code within in them is very similar.

Does anyone have any ideas on how I could better write this to avoid code duplication:

(async (): Promise<void> => {

    // 1 min interval check
    const oneMin = setInterval(async function () {
        Detail.find({ interval: 1 }, async function (err, toCheck) {
            // The Same Logic
        })
    }, minutesToMS(1));

    // 10 min interval check
    const tenMin = setInterval(async function () {
        Detail.find({ interval: 10 }, async function (err, toCheck) {
            // The Same Logic
        })
    }, minutesToMS(10));

})();

Any ideas appreciated.

Thanks.

CertainPerformance · Accepted Answer · 2020-05-08 14:25:19Z

2

Put this part:

async function (err, toCheck) {
  // The Same Logic
}

into a standalone variable first, so you can pass it to both .finds:

type CallbackType = Parameters<typeof Detail.find>[1];
const callback: CallbackType = async (err, toCheck) => {
    // logic
};
// 1 min interval check
setInterval(function () {
    Detail.find({ interval: 1 }, callback)
}, minutesToMS(1));

// 10 min interval check
setInterval(function () {
    Detail.find({ interval: 10 }, callback)
}, minutesToMS(10));

If you also want to avoid repeating the { interval: 1 } minutesToMS(1), then:

type CallbackType = Parameters<typeof Detail.find>[1];
const callback: CallbackType = async (err, toCheck) => {
    // logic
};
const makeInterval = (interval) => {
    setInterval(function () {
        Detail.find({ interval }, callback)
    }, minutesToMS(interval));
};
makeInterval(1);
makeInterval(10);

edited May 8, 2020 at 14:25

answered May 8, 2020 at 14:09

CertainPerformance

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8 Comments

userMod2 Over a year ago

Cool - that looks good. By the way having those multiple setIntervals in one function, I had to declare each setInterval into its own variable like const oneMin, const tenMin etc. It works, but of course my linter complains about the unused variable. Any ideas on that?

CertainPerformance Over a year ago

If you only need to initialize the interval, but not use the returned interval ID, then just don't assign the result to a variable

userMod2 Over a year ago

Also in the line type CallbackType = Parameters<typeof Detail.find>[1] what does that [1] refer to? DIdnt quite understand it

Aluan Haddad Over a year ago

This is good, but you could go a step further and create: function createSetInterval(interval: number) { return setInterval(....); }

CertainPerformance Over a year ago

The question is tagged with Typescript, so I assume this is TS - if you want the callback function (its parameters and return type) to be typed correctly, TS needs to know its shape. This can be done by either listing all the possible types manually, or (a better option) by using Parameters to extract the type of the Details.find function, and [1] to extract the second parameter

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