[{"data":1,"prerenderedAt":148},["ShallowReactive",2],{"page:/zh/milliseconds":3},{"id":4,"title":5,"body":6,"description":124,"extension":125,"eyebrow":126,"faq":127,"locale":137,"meta":138,"navigation":139,"pageType":140,"path":141,"related":142,"seo":143,"stem":146,"__hash__":147},"pages/zh/milliseconds.md","当前毫秒时间戳",{"type":7,"value":8,"toc":114},"minimark",[9,14,18,22,29,32,35,38,41,44,102,105],[10,11,13],"h2",{"id":12},"为什么当前毫秒通常是-13-位","为什么当前毫秒通常是 13 位？",[15,16,17],"p",{},"当前日期距离 Unix 纪元约有 1.7 万亿毫秒，因此现代正数通常有 13 位。位数会随日期变化：接近 1970 年的值更短，负数带符号，未来数值会继续增长，所以不能把“13 位”当作唯一验证条件。",[10,19,21],{"id":20},"javascript-与精度","JavaScript 与精度",[15,23,24,28],{},[25,26,27],"code",{},"Date.now()"," 返回来自设备时钟的整数毫秒。把该值乘以 1,000 或 1,000,000，可以分别表达微秒或纳秒单位，但不会产生新的计时精度。需要真实亚毫秒测量的系统应使用合适的高精度时钟，并明确它与 Unix 纪元之间的关系。",[10,30,31],{"id":31},"存储与接口注意事项",[15,33,34],{},"在数据库或 API 中，应同时记录字段单位。秒值写入毫秒字段会落在 1970 年附近，毫秒值写入秒字段则可能溢出或得到遥远未来日期。JavaScript 普通 Number 也有安全整数上限；处理 16 位或 19 位值时，应避免在换算前发生舍入。",[10,36,37],{"id":37},"具体怎么使用",[15,39,40],{},"当接口或数据库字段注明使用毫秒时，复制毫秒行。秒行把同一个设备读数除以 1,000；微秒和纳秒行只是换算单位，并不是独立的高精度测量。",[10,42,43],{"id":43},"输入与输出示例",[45,46,47,60],"table",{},[48,49,50],"thead",{},[51,52,53,57],"tr",{},[54,55,56],"th",{},"输入或设置",[54,58,59],{},"预期结果",[61,62,63,78,90],"tbody",{},[51,64,65,72],{},[66,67,68,71],"td",{},[25,69,70],{},"1700000000"," · s",[66,73,74,77],{},[25,75,76],{},"1700000000000"," · ms",[51,79,80,84],{},[66,81,82,77],{},[25,83,76],{},[66,85,86,89],{},[25,87,88],{},"1700000000000000"," · µs",[51,91,92,96],{},[66,93,94,77],{},[25,95,76],{},[66,97,98,101],{},[25,99,100],{},"1700000000000000000"," · ns",[10,103,104],{"id":104},"使用结果前的检查",[15,106,107,108,113],{},"设备时钟不准，当前数值也会不准，本页不会通过外部授时服务校准设备。已有存储数值请到",[109,110,112],"a",{"href":111},"/zh/timestamp-to-date/","时间戳转日期","并选择毫秒。程序运行耗时应使用单调时钟，因为系统校时可能改变日历时间。",{"title":115,"searchDepth":116,"depth":116,"links":117},"",2,[118,119,120,121,122,123],{"id":12,"depth":116,"text":13},{"id":20,"depth":116,"text":21},{"id":31,"depth":116,"text":31},{"id":37,"depth":116,"text":37},{"id":43,"depth":116,"text":43},{"id":104,"depth":116,"text":104},"复制当前 13 位 Unix 毫秒数，并与秒、微秒和纳秒单位进行比较。","md","实时精度 / 03",[128,131,134],{"question":129,"answer":130},"当前毫秒时间戳为什么通常是 13 位？","当代日期距离 1970 年纪元约有 1.7 万亿毫秒，因此正数通常为 13 位；较早或遥远未来的日期可能不是 13 位。",{"question":132,"answer":133},"Date.now() 返回的是什么？","JavaScript Date.now() 返回设备时钟对应的 Unix 毫秒整数。",{"question":135,"answer":136},"把毫秒乘一百万就是精确纳秒吗？","不是。这样只能表示纳秒单位，新增的末尾零并不是设备实际测得的亚毫秒精度。","zh",{},true,"tool","/zh/milliseconds",null,{"title":144,"description":145},"当前毫秒时间戳 — 实时 Unix 毫秒数","获取当前 13 位 Unix 毫秒时间戳，并查看秒、微秒、纳秒以及安全转换说明。","zh/milliseconds","V7mipApQ4Nye0sq0qWZK0rmYGoGx1NbLOAEmRyNdonQ",1792032485494]