在此页

• 句法
• Reduced time precision
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

getTime() method returns the number of milliseconds* since the Unix Epoch .

* JavaScript uses 毫秒 as the unit of measurement, whereas Unix Time is in 秒。

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 object. This method is functionally equivalent to the valueOf() 方法。

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

句法

dateObj.getTime()
					

返回值

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

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 20µs in Firefox 59; in 60 it will be 2ms.

// 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 enable privacy.resistFingerprinting , the precision will be 100ms or the value of privacy.resistFingerprinting.reduceTimerPrecision.microseconds , whichever is larger.

范例

使用 getTime() for copying dates

Constructing a date object with the identical time value.

// 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

Subtracting two subsequent getTime() calls on newly generated 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() to prevent instantiating unnecessary Date 对象。

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');
					

规范

规范
ECMAScript (ECMA-262) The definition of 'Date.prototype.getTime' in that specification.

浏览器兼容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

更新 GitHub 上的兼容性数据

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
getTime	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100

图例

完整支持

完整支持

另请参阅

• Date.prototype.setTime()
• Date.prototype.valueOf()
• Date.now()

元数据

• 最后修改： May 20, 2020

相关话题

1. 标准内置对象
2. Date
3. 方法
   1. Date.UTC()
   2. Date.now()
   3. Date.parse()
   4. Date.prototype.getDate()
   5. Date.prototype.getDay()
   6. Date.prototype.getFullYear()
   7. Date.prototype.getHours()
   8. Date.prototype.getMilliseconds()
   9. Date.prototype.getMinutes()
   10. Date.prototype.getMonth()
   11. Date.prototype.getSeconds()
   12. Date.prototype.getTime()
   13. Date.prototype.getTimezoneOffset()
   14. Date.prototype.getUTCDate()
   15. Date.prototype.getUTCDay()
   16. Date.prototype.getUTCFullYear()
   17. Date.prototype.getUTCHours()
   18. Date.prototype.getUTCMilliseconds()
   19. Date.prototype.getUTCMinutes()
   20. Date.prototype.getUTCMonth()
   21. Date.prototype.getUTCSeconds()
   22. Date.prototype.getYear()
   23. Date.prototype.setDate()
   24. Date.prototype.setFullYear()
   25. Date.prototype.setHours()
   26. Date.prototype.setMilliseconds()
   27. Date.prototype.setMinutes()
   28. Date.prototype.setMonth()
   29. Date.prototype.setSeconds()
   30. Date.prototype.setTime()
   31. Date.prototype.setUTCDate()
   32. Date.prototype.setUTCFullYear()
   33. Date.prototype.setUTCHours()
   34. Date.prototype.setUTCMilliseconds()
   35. Date.prototype.setUTCMinutes()
   36. Date.prototype.setUTCMonth()
   37. Date.prototype.setUTCSeconds()
   38. Date.prototype.setYear()
   39. Date.prototype.toDateString()
   40. Date.prototype.toGMTString()
   41. Date.prototype.toISOString()
   42. Date.prototype.toJSON()
   43. Date.prototype.toLocaleDateString()
   44. Date.prototype.toLocaleString()
   45. Date.prototype.toLocaleTimeString()
   46. Date.prototype.toSource()
   47. Date.prototype.toString()
   48. Date.prototype.toTimeString()
   49. Date.prototype.toUTCString()
   50. Date.prototype.valueOf()
   51. Date.prototype[@@toPrimitive]
4. 继承：
5. Function
6. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
7. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
8. Object
9. 特性
   1. Object.prototype.__proto__
   2. Object.prototype.constructor
10. 方法
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toSource()
    10. Object.prototype.toString()
    11. Object.prototype.valueOf()
    12. Object.setPrototypeOf()