How to Calculate the Time Difference Between Two Times in JavaScript?

Determine Time Difference in JavaScript

Calculating the time difference between two text-boxes in JavaScript can be accomplished through the following approach:

Step 1: Convert Strings to Date Objects

Begin by creating two Date objects from the text-box strings. Specify an arbitrary date part, the input time, and set the timezone to UTC.

let time1 = "09:00";
let time2 = "17:00";

let date1 = new Date(`2000-01-01T${time1}Z`);
let date2 = new Date(`2000-01-01T${time2}Z`);

Step 2: Adjust for Times Crossing Midnight

In some scenarios, the times may span midnight. To handle this, check if the second date is earlier than the first. If so, add a day to the second date.

if (date2 < date1) {
  date2.setDate(date2.getDate() + 1);
}

Step 3: Calculate the Difference

Subtract the first date object from the second to obtain the difference in milliseconds.

let diff = date2 - date1;

Step 4: Format the Result

Depending on the display requirements, you can format the result as needed.

For example, to display the difference as a time string:

let hours = Math.floor(diff / (1000 * 60 * 60));
let minutes = Math.floor((diff / (1000 * 60)) % 60);
let result = `${hours < 10 ? '0' + hours : hours}:${minutes < 10 ? '0' + minutes : minutes}`;

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