To add seconds to date in JavaScript:

  1. Use the getSeconds() method to get the seconds of the given date.
  2. Use the setSeconds() method by passing the result returned by getSeconds() plus the number of seconds you want to add.
  3. The setSeconds() method sets the value on the given date.

Here is an example that adds 10 seconds to the current date in JavaScript:

const today = new Date()
today.setSeconds(today.getSeconds() + 10)

console.log(today)
// Sat Sep 10 2022 22:47:41 GMT+0500 (Pakistan Standard Time)

The getSeconds() method returns a number between 0 and 59, denoting the number of seconds of the given date.

The setSeconds() method takes a number as input representing the number of seconds and sets the value on the date.

The above methods also take care of the situation where adding a specific number of seconds to date results in the next day, month, or year:

const date = new Date('2022-09-10T23:33:45.900Z')
date.setSeconds(date.getSeconds() + 30)

console.log(date.toUTCString())
// Sat, 10 Sep 2022 23:34:15 GMT

If you often need to add seconds to date, just create a reusable function that takes the number of seconds as a parameter and adds them to the current date:

Date.prototype.addSeconds = function (secs) {
  const date = new Date(this.valueOf())
  date.setSeconds(date.getSeconds() + secs)
  return date
}

const date = new Date('2022-09-10T16:23:45.900Z')

// Add 45 Seconds
const result = date.addSeconds(45)

console.log(result.toUTCString())
// Sat, 10 Sep 2022 16:24:30 GMT

In the above example, we added a function called addSeconds() to the Date object prototype. This function will be available to all instances of Date for adding seconds to date.

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