Question 299434 in Javascript Question posted in
A very good W3school tutorial can be found here.

Javascript – Add one milliseconds to the tick

I have a tick data as 638315425210000000 and 638338147200000000 need to add/subtract one milliseconds from it, and for the same I’m using the below specified code lines

let ticksInMilliseconds = 10000
//to add milliseconds to tick
const startTick = 638315425210000000
const millisecondsAdded = startTick +  ticksInMilliseconds 
//to reduce one millisecond
const endTick = 638338147200000000
const millisecondReduced = endTick - ticksInMilliseconds

For millisecondsAdded I get tick value as (638315425210010000) and for millisecondReduced get tick value as 638338147199990000

When converted to dates online to check if the milliseconds value are added/reduced the millisecondReduced gave correct value, but the millisecondsAdded still shows the same time with no milliseconds added 2023-09-29​T00:02:01.000Z

I would like to understand why add is not adding millisecond to the tick and what should be the solution for the same

For conversion online I used https://tickstodatetime.azurewebsites.net/ which accepts the values I paste

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2

Answers


  1. 0

    your number is above the max safe integer value and operations aren’t reliable on integers at that point. You could use a Big integer to keep precision at that point

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  2. 0

    So testing this in Chrome on Win10, which allows such large numbers.

    The code works if I actually subtract ticksInMilliseconds. You added in both cases.

    HOWEVER the website you posted does not work on 10000 added.

    638315425210000000 is 2023-09-29​T00:02:01.000Z and 1 tick more is
    638315425210010000 is 2023-09-29​T00:02:01.000Z which is the same according to the site

    Whereas

    638338147200000000 is 2023-10-25​T07:12:00.000Z and one tick less

    638338147199990000 is 2023-10-25​T07:11:59.999Z IS one millisecond less

    I have raised an issue

    let ticksInMilliseconds = 10000
//to add milliseconds to tick
const startTick = "638315425210000000"; // valid INT in Chrome
console.log("str",startTick,"int",+startTick)
const millisecondsAdded = (+startTick) +  ticksInMilliseconds 
//to reduce one millisecond
const endTick = "638338147200000000"
const millisecondReduced = (+endTick) - ticksInMilliseconds

console.log(startTick,millisecondsAdded)
console.log(endTick,millisecondReduced)
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