You can get the client’s timezone offset by using the Date object’s getTimezoneOffset() method:
The method of toString() can be useful if you want the client timezone to be formatted:
In the ECMAScript 2015 Internationalization API version, the timeZone property will be the name of the default time zone if no timeZone property was provided in the options object provided to the Intl.DateTimeFormat constructor. in previous versions, it will return undefined.
The Intl.DateTimeFormat constructor is for objects enabling language-sensitive date and time formatting.
The getTimezoneOffset() Method
The getTimezoneOffset() method represents the time difference between the UTC time and the local time, in minutes. It returns non-constant value because of the practice of using Daylight Saving Time.
The toString() Method
The toString() method returns a string representing the specified Date object. Date instances inherit their toString() method from Date.prototype. The Date.prototype.toString() returns a string representation of the Date in the format that is specified in ECMA-262.