var mydate;
    mydate = new Date();
    document.getElementById('clockinhour').value = mydate.toISOString().slice(0, 19).replace('T', ' ');
Output A
2017-06-21 20:14:31 
this is inserting as varchar :
document.getElementById('clocked_in_time').value = Date();
Output B
Wed Jun 21 2017 16:14:31 GMT-0400 (Eastern Standard Time)
Output B is the correct time but I need to display output A. What causes the time to change when converted toISOString? How can I fix this?
                Output B is the correct time but I need to display output A, do you mean display in the format that output A is?
                    – Patrick Roberts
                Jun 22 '17 at 3:51
                Does this mean you would like to display the date time in EST format and not ISO format?
                    – Jaya
                Jun 22 '17 at 3:51
                Possible duplicate of What's the difference between datetime in ISO 8601 and UTC formats in javascript?
                    – Pratik Ghag
                Jun 22 '17 at 4:31
        
In your this is inserting as Datetime block your slice are stripping of the timezone part (the Z at the end of toISOString output):
document.getElementById('clockinhour').value = mydate.toISOString().slice(0, 19).replace('T', ' ');
As pointed out by @RobG in the comments section, toISOString should always return the date in UTC (Z or +00:00).
  
RTFM:
  "The time zone [offset] is always UTC, denoted by the suffix Z",
The time "changes" because it is converted to UTC when you calls toISOString.
If you want to get ISO date in your timezone, you should take a look in these two questions: How to ISO 8601 format a Date with Timezone Offset in JavaScript? and How to format a JavaScript date
        
Just if someone else face the same issue and visit this question.
There is a solution here:
https://stackoverflow.com/a/28149561
        
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