# Date.getTime()

The getTime() method returns the numeric value corresponding to the time for the specified date according to universal time.

*getTime() always uses UTC for time representation. For example, a client browser in one timezone, getTime() will be the same as a client browser in any other timezone.*

You can use this method to help assign a date and time to another [`Date`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date) object. This method is functionally equivalent to the [`valueOf()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/valueof) method.

```javascript
var moonLanding = new Date('July 20, 69 00:20:18 GMT+00:00');

// milliseconds since Jan 1, 1970, 00:00:00.000 GMT
console.log(moonLanding.getTime());
// expected output: -14254782000

```

## Syntax <a href="#syntax" id="syntax"></a>

```javascript
dateObj.getTime()
```

**Return value**

A number representing the milliseconds elapsed between 1 January 1970 00:00:00 UTC and the given date.

## Examples <a href="#examples" id="examples"></a>

#### Using `getTime()` for copying dates <a href="#using_gettime-_for_copying_dates" id="using_gettime-_for_copying_dates"></a>

Constructing a date object with the identical time value.

```javascript
// Since month is zero based, birthday will be January 10, 1995
var birthday = new Date(1994, 12, 10);
var copy = new Date();
copy.setTime(birthday.getTime());
```

#### Measuring execution time <a href="#measuring_execution_time" id="measuring_execution_time"></a>

Subtracting two subsequent `getTime()` calls on newly generated [`Date`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date) objects, give the time span between these two calls. This can be used to calculate the executing time of some operations. See also [`Date.now()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/now) to prevent instantiating unnecessary [`Date`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date)objects.

```javascript
var end, start;

start = new Date();
for (var i = 0; i < 1000; i++) {
  Math.sqrt(i);
}
end = new Date();

console.log('Operation took ' + (end.getTime() - start.getTime()) + ' msec');
```

## Reduced time precision

To offer protection against timing attacks and fingerprinting, the precision of `new Date().getTime()` might get rounded depending on browser settings.\
In Firefox, the `privacy.reduceTimerPrecision`  preference is enabled by default and defaults to 20us in Firefox 59; in 60 it will be 2ms.

```javascript
// reduced time precision (2ms) in Firefox 60
new Date().getTime();
// 1519211809934
// 1519211810362
// 1519211811670
// ...


// reduced time precision with `privacy.resistFingerprinting` enabled
new Date().getTime();
// 1519129853500
// 1519129858900
// 1519129864400
// ...
```

In Firefox, you can also enabled `privacy.resistFingerprinting`, the precision will be 100ms or the value of `privacy.resistFingerprinting.reduceTimerPrecision.microseconds`, whichever is larger.

## References <a href="#references" id="references"></a>

{% embed url="<https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/getTime>" %}

## Contributors to this page <a href="#contributors-to-this-page" id="contributors-to-this-page"></a>

Uros Durdevic