Solution 1 :

The html input validation only works / activates on the submit button. The input will always let the user write, pick or select whatever he wants. The form action will be blocked if the inputs are not filled out correctly, and the out of the box tiptool will be displayed.

If by any chance you are referring for the time input validation not to work correctly, the mdn documentation states that you should use 24h time format to limit the times that the input can take.

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/time

<input type="time" id="appt" name="appt"
       min="09:00" max="18:00" required>

Problem :

I am trying to give min value in Html input time type. But it does not affect the result. I also tried with moment but the result did not change. How can I do this in Html without using any external library?
PS: I am using react js. this input type is inside jsx

<input
 onChange={e => setOptionHour2(e.target.value)} 
 defaultValue={props.min} 
 min={"2021-01-07T15:00:00"} //{props.min}
 type="time"
 id="appt2"
 name="appt"/>

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