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ViewsAdding seconds to javascript DateTime object through the use of a prompt
I have this webpage that takes in an input in seconds, and produces what the time will be after the time has elapsed. So I went about it using the following code
let duration = prompt("Enter your trip duration in seconds: "); // get the time from the vaue of the input element
let newtime = new Date(); // get the current time
newtime.setSeconds(newtime.getSeconds() + duration)
I decided to test the code and it gave me weird results and for some reason when I divided the duration by ten it started to work. Even though it worked I wasn't satisfied. So I added some more code to try and find where the bug is.
let oldtime = new Date();
oldtime.setSeconds(oldtime.getSeconds() + 60);
I added some code so that it would show on the webpage to compare the two times and these are my results when I enter 60 as the duration...
Just a little summary. The code works when I hard code the values in but it behaves weirdly if I try get the input from a prompt
3 answers
Answer question0
You are concatenating a string to a number instead of adding. You have to parse the result from prompt to a number (with the unary plus operator):
let duration = prompt("Enter your trip duration in seconds: "); // get the time from the vaue of the input element
let newtime = new Date(); // get the current time
newtime.setSeconds(newtime.getSeconds() + +duration)
console.log(newtime)0
I believe the issue is because you need to parse the duration from a string to number. So, try this
newtime.setSeconds(newtime.getSeconds() + parseInt(duration, 10))
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You can use a library like Luxon to deal with dates and times without having to worry about unexpected behaviour like the one you described.
import { DateTime } from "luxon";
const now = DateTime.now();
const timeAfterTrip.plus({ seconds: duration });
console.log(timeAfterTrip);