Category: JavaScript Answers

Sometimes, we want to add open-ended function arguments with TypeScript.

In this article, we’ll look at how to add open-ended function arguments with TypeScript.

How to add open-ended function arguments with TypeScript?

To add open-ended function arguments with TypeScript, we can use the rest syntax.

For instance, we write

const sum = (...numbers: number[]) => {
  let aggregateNumber = 0;
  for (const n of numbers) {
    aggregateNumber += n;
  }
  return aggregateNumber;
};

console.log(sum(1, 5, 10, 15, 20));

to create the sum function.

We make it accept an unlimited number of arguments with ...numbers.

And we get the arguments as an array.

We set the type to number[] so that numbers would be an array of numbers.

Then we loop through the numbers entries and add them to aggregateNumber.

And finally, we return the result.

Conclusion

To add open-ended function arguments with TypeScript, we can use the rest syntax.

Sometimes, we want to change the background color with JavaScript.

In this article, we’ll look at how to change the background color with JavaScript.

How to change the background color with JavaScript?

To change the background color with JavaScript, we can set the style.background property of an element.

For instance, we write

document.body.style.background = color;

to set the body element’s background color to color.

We get the body element’s background color with

document.body.style.background

Conclusion

To change the background color with JavaScript, we can set the style.background property of an element.

Sometimes, we want to loop through a date range with JavaScript.

In this article, we’ll look at how to loop through a date range with JavaScript.

How to loop through a date range with JavaScript?

To loop through a date range with JavaScript, we can use a while loop.

For instance, we write

let start = new Date("02/05/2022");
let end = new Date("02/10/2022");

let loop = new Date(start);
while (loop <= end) {
  console.log(loop);
  const newDate = loop.setDate(loop.getDate() + 1);
  loop = new Date(newDate);
}

to create the start and end dates.

Then we create the loop date from the start date that we use as the loop variable.

Next, we add a while loop that runs while loop is less than or equal to end.

In it, we log the loop variable.

Then we call setDate with loop.getDate() + 1 to create newDate.

And then we update loop to newDate with

loop = new Date(newDate)

Conclusion

To loop through a date range with JavaScript, we can use a while loop.

Sometimes, we want to get tomorrow, today and yesterday with moment.js and JavaScript.

In this article, we’ll look at how to get tomorrow, today and yesterday with moment.js and JavaScript.

How to get tomorrow, today and yesterday with moment.js and JavaScript?

To get tomorrow, today and yesterday with moment.js and JavaScript, we can use the add method.

For instance, we write

let today = moment();
let tomorrow = moment().add(1, "days");
let yesterday = moment().add(-1, "days");

to get today’s date as a moment object with

let today = moment();

We call add with 1 and 'days' on the moment object for the current date time to get tomorrow’s date.

And we call add with -1 and 'days' on the moment object for the current date time to get yesterday’s date.

Sometimes, we want to get the number of years since a date, not rounded up with Moment.js and JavaScript.

In this article, we’ll look at how to get the number of years since a date, not rounded up with Moment.js and JavaScript.

How to get the number of years since a date, not rounded up with Moment.js and JavaScript?

To get the number of years since a date, not rounded up with Moment.js and JavaScript, we call the diff method.

For instance, we write

const years = moment().diff("1981-01-01", "years");

to get the number of years difference between today and January 1, 1981.

We call moment with nothing to get the current datetime as a moment object.

Then we call diff with the date string and 'years' to get the years difference.

Conclusion

To get the number of years since a date, not rounded up with Moment.js, we call the diff method.