JavaScript获取时间戳的坑

JavaScript获取时间戳的三个方法：

• Date.parse(new Date())
  获取13位时间戳，例如00，
  
  
• (new Date()).valueOf()
  获取13位时间戳，精确到毫秒，例如：49
  
  
• new Date().getTime()。
  获取13位时间戳，精确到毫秒，例如：25
  
  

示例

以上面第一种方法为例

 
timestamp
 点击这里，显示时间戳  

上述页面中的脚本执行后，会返回13位数字，如：49。parse方法会解析包含日期的字符串，并返回该日期与1970年1月1日午夜之间的毫秒数（UTC时间）。而上面parse解析的字符串是通过new Date()方法来获取到的，从下面的内容来看，new Date()获取的是一个当前主机的本地时间。

/ Enables basic storage and retrieval of dates and times. */ interface Date { / Returns a string representation of a date. The format of the string depends on the locale. */ toString(): string; / Returns a date as a string value. */ toDateString(): string; / Returns a time as a string value. */ toTimeString(): string; / Returns a value as a string value appropriate to the host environment's current locale. */ toLocaleString(): string; / Returns a date as a string value appropriate to the host environment's current locale. */ toLocaleDateString(): string; / Returns a time as a string value appropriate to the host environment's current locale. */ toLocaleTimeString(): string; / Returns the stored time value in milliseconds since midnight, January 1, 1970 UTC. */ valueOf(): number; / Gets the time value in milliseconds. */ getTime(): number; / Gets the year, using local time. */ getFullYear(): number; / Gets the year using Universal Coordinated Time (UTC). */ getUTCFullYear(): number; / Gets the month, using local time. */ getMonth(): number; / Gets the month of a Date object using Universal Coordinated Time (UTC). */ getUTCMonth(): number; / Gets the day-of-the-month, using local time. */ getDate(): number; / Gets the day-of-the-month, using Universal Coordinated Time (UTC). */ getUTCDate(): number; / Gets the day of the week, using local time. */ getDay(): number; / Gets the day of the week using Universal Coordinated Time (UTC). */ getUTCDay(): number; / Gets the hours in a date, using local time. */ getHours(): number; / Gets the hours value in a Date object using Universal Coordinated Time (UTC). */ getUTCHours(): number; / Gets the minutes of a Date object, using local time. */ getMinutes(): number; / Gets the minutes of a Date object using Universal Coordinated Time (UTC). */ getUTCMinutes(): number; / Gets the seconds of a Date object, using local time. */ getSeconds(): number; / Gets the seconds of a Date object using Universal Coordinated Time (UTC). */ getUTCSeconds(): number; / Gets the milliseconds of a Date, using local time. */ getMilliseconds(): number; / Gets the milliseconds of a Date object using Universal Coordinated Time (UTC). */ getUTCMilliseconds(): number; / Gets the difference in minutes between the time on the local computer and Universal Coordinated Time (UTC). */ getTimezoneOffset(): number; / * Sets the date and time value in the Date object. * @param time A numeric value representing the number of elapsed milliseconds since midnight, January 1, 1970 GMT. */ setTime(time: number): number; / * Sets the milliseconds value in the Date object using local time. * @param ms A numeric value equal to the millisecond value. */ setMilliseconds(ms: number): number; / * Sets the milliseconds value in the Date object using Universal Coordinated Time (UTC). * @param ms A numeric value equal to the millisecond value. */ setUTCMilliseconds(ms: number): number; / * Sets the seconds value in the Date object using local time. * @param sec A numeric value equal to the seconds value. * @param ms A numeric value equal to the milliseconds value. */ setSeconds(sec: number, ms?: number): number; / * Sets the seconds value in the Date object using Universal Coordinated Time (UTC). * @param sec A numeric value equal to the seconds value. * @param ms A numeric value equal to the milliseconds value. */ setUTCSeconds(sec: number, ms?: number): number; / * Sets the minutes value in the Date object using local time. * @param min A numeric value equal to the minutes value. * @param sec A numeric value equal to the seconds value. * @param ms A numeric value equal to the milliseconds value. */ setMinutes(min: number, sec?: number, ms?: number): number; / * Sets the minutes value in the Date object using Universal Coordinated Time (UTC). * @param min A numeric value equal to the minutes value. * @param sec A numeric value equal to the seconds value. * @param ms A numeric value equal to the milliseconds value. */ setUTCMinutes(min: number, sec?: number, ms?: number): number; / * Sets the hour value in the Date object using local time. * @param hours A numeric value equal to the hours value. * @param min A numeric value equal to the minutes value. * @param sec A numeric value equal to the seconds value. * @param ms A numeric value equal to the milliseconds value. */ setHours(hours: number, min?: number, sec?: number, ms?: number): number; / * Sets the hours value in the Date object using Universal Coordinated Time (UTC). * @param hours A numeric value equal to the hours value. * @param min A numeric value equal to the minutes value. * @param sec A numeric value equal to the seconds value. * @param ms A numeric value equal to the milliseconds value. */ setUTCHours(hours: number, min?: number, sec?: number, ms?: number): number; / * Sets the numeric day-of-the-month value of the Date object using local time. * @param date A numeric value equal to the day of the month. */ setDate(date: number): number; / * Sets the numeric day of the month in the Date object using Universal Coordinated Time (UTC). * @param date A numeric value equal to the day of the month. */ setUTCDate(date: number): number; / * Sets the month value in the Date object using local time. * @param month A numeric value equal to the month. The value for January is 0, and other month values follow consecutively. * @param date A numeric value representing the day of the month. If this value is not supplied, the value from a call to the getDate method is used. */ setMonth(month: number, date?: number): number; / * Sets the month value in the Date object using Universal Coordinated Time (UTC). * @param month A numeric value equal to the month. The value for January is 0, and other month values follow consecutively. * @param date A numeric value representing the day of the month. If it is not supplied, the value from a call to the getUTCDate method is used. */ setUTCMonth(month: number, date?: number): number; / * Sets the year of the Date object using local time. * @param year A numeric value for the year. * @param month A zero-based numeric value for the month (0 for January, 11 for December). Must be specified if numDate is specified. * @param date A numeric value equal for the day of the month. */ setFullYear(year: number, month?: number, date?: number): number; / * Sets the year value in the Date object using Universal Coordinated Time (UTC). * @param year A numeric value equal to the year. * @param month A numeric value equal to the month. The value for January is 0, and other month values follow consecutively. Must be supplied if numDate is supplied. * @param date A numeric value equal to the day of the month. */ setUTCFullYear(year: number, month?: number, date?: number): number; / Returns a date converted to a string using Universal Coordinated Time (UTC). */ toUTCString(): string; / Returns a date as a string value in ISO format. */ toISOString(): string; / Used by the JSON.stringify method to enable the transformation of an object's data for JavaScript Object Notation (JSON) serialization. */ toJSON(key?: any): string; } interface DateConstructor { new(): Date; new(value: number | string): Date; new(year: number, month: number, date?: number, hours?: number, minutes?: number, seconds?: number, ms?: number): Date; (): string; readonly prototype: Date; / * Parses a string containing a date, and returns the number of milliseconds between that date and midnight, January 1, 1970. * @param s A date string */ parse(s: string): number; / * Returns the number of milliseconds between midnight, January 1, 1970 Universal Coordinated Time (UTC) (or GMT) and the specified date. * @param year The full year designation is required for cross-century date accuracy. If year is between 0 and 99 is used, then year is assumed to be 1900 + year. * @param month The month as an number between 0 and 11 (January to December). * @param date The date as an number between 1 and 31. * @param hours Must be supplied if minutes is supplied. An number from 0 to 23 (midnight to 11pm) that specifies the hour. * @param minutes Must be supplied if seconds is supplied. An number from 0 to 59 that specifies the minutes. * @param seconds Must be supplied if milliseconds is supplied. An number from 0 to 59 that specifies the seconds. * @param ms An number from 0 to 999 that specifies the milliseconds. */ UTC(year: number, month: number, date?: number, hours?: number, minutes?: number, seconds?: number, ms?: number): number; now(): number; } 

问题来了，一般服务器的时间是固定的，但是客户端且分布世界各地，客户端系统设置的时间也不一定按标准时区分布。因此就会造成通过JavaScript得到的时间戳不准确。