The setHours() method sets the hours for a specified date according to local time, and returns the number of milliseconds since 1 January 1970 00:00:00 UTC until the time represented by the updated Date instance.
dateObj.setHours(hoursValue[, minutesValue[, secondsValue[, msValue]]])
dateObj.setHours(hoursValue)
hoursValueminutesValuesecondsValuesecondsValue parameter, you must also specify the minutesValue.msValuemsValue parameter, you must also specify the minutesValue and secondsValue.If you do not specify the minutesValue, secondsValue, and msValue parameters, the values returned from the getMinutes(), getSeconds(), and getMilliseconds() methods are used.
If a parameter you specify is outside of the expected range, setHours() attempts to update the date information in the Date object accordingly. For example, if you use 100 for secondsValue, the minutes will be incremented by 1 (minutesValue + 1), and 40 will be used for seconds.
setHours()var theBigDay = new Date(); theBigDay.setHours(7);
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