Check out example codes for "type time html returns 24 hour time change to 12 hour". It will help you in understanding the concepts better.
Code Example 1
If your computer's system prefs are set to use a 24-hour clock, the browser will render the <input type="time"> element as --:-- (time range: 00:00–23:59). If you change your computer's syst prefs to use 12-hour, the output won't change until you quit and relaunch the browser.
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