fingerprintjs

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import { toFloat } from '../utils/data'
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export default function getTimezone(): string {
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  const DateTimeFormat = window.Intl?.DateTimeFormat
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  if (DateTimeFormat) {
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    const timezone = new DateTimeFormat().resolvedOptions().timeZone
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    if (timezone) {
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      return timezone
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    }
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  }
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  // For browsers that don't support timezone names
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  // The minus is intentional because the JS offset is opposite to the real offset
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  const offset = -getTimezoneOffset()
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  return `UTC${offset >= 0 ? '+' : ''}${offset}`
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}
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function getTimezoneOffset(): number {
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  const currentYear = new Date().getFullYear()
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  // The timezone offset may change over time due to daylight saving time (DST) shifts.
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  // The non-DST timezone offset is used as the result timezone offset.
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  // Since the DST season differs in the northern and the southern hemispheres,
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  // both January and July timezones offsets are considered.
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  return Math.max(
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    // `getTimezoneOffset` returns a number as a string in some unidentified cases
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    toFloat(new Date(currentYear, 0, 1).getTimezoneOffset()),
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    toFloat(new Date(currentYear, 6, 1).getTimezoneOffset()),
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  )
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}
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