How to ISO 8601 format a Date with Timezone Offset in JavaScript?

Question

Goal: Find the local time and UTC time offset then construct the URL in following format.

Example URL: /Actions/Sleep?dura

Answer 1

Check this:

function dateToLocalISO(date) {
    const off    = date.getTimezoneOffset()
    const absoff = Math.abs(off)
    return (new Date(date.getTime() - off*60*1000).toISOString().substr(0,23) +
            (off > 0 ? '-' : '+') + 
            (absoff / 60).toFixed(0).padStart(2,'0') + ':' + 
            (absoff % 60).toString().padStart(2,'0'))
}

// Test it:
d = new Date()

dateToLocalISO(d)
// ==> '2019-06-21T16:07:22.181-03:00'

// Is similar to:

moment = require('moment')
moment(d).format('YYYY-MM-DDTHH:mm:ss.SSSZ') 
// ==> '2019-06-21T16:07:22.181-03:00'