[{"data":1,"prerenderedAt":148},["ShallowReactive",2],{"page:/zh-TW/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-TW/milliseconds.md","目前的毫秒時間戳",{"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},"為什麼目前毫秒通常是-13-位","為什麼目前毫秒通常是 13 位？",[15,16,17],"p",{},"目前日期距離 Unix 紀元約有 1.7 兆毫秒，因此現代正數通常有 13 位。位數會隨日期變化：接近 1970 年的值較短，負數帶符號，未來數值會繼續增加，所以不能把「13 位」當作唯一驗證條件。",[10,19,21],{"id":20},"javascript-與精度","JavaScript 與精度",[15,23,24,28],{},[25,26,27],"code",{},"Date.now()"," 傳回來自裝置時鐘的整數毫秒。將該值乘以 1,000 或 1,000,000，可以分別表達微秒或奈秒單位，但不會產生新的計時精度。需要真正次毫秒量測的系統應使用合適的高精度時鐘，並明確定義它與 Unix 紀元的關係。",[10,30,31],{"id":31},"儲存與介面注意事項",[15,33,34],{},"在資料庫或 API 中，應同時記錄欄位單位。秒值寫入毫秒欄位會落在 1970 年附近，毫秒值寫入秒欄位則可能溢位或得到遙遠未來日期。JavaScript 一般 Number 也有安全整數上限；處理 16 位或 19 位值時，應避免在換算前發生捨入。",[10,36,37],{"id":37},"如何操作這個工具",[15,39,40],{},"介面或資料庫註明毫秒時，複製毫秒行。秒行將同一裝置讀數除以 1,000；微秒與奈秒只是單位換算，並非獨立的高精度量測。",[10,42,43],{"id":43},"輸入與輸出範例",[45,46,47,60],"table",{},[48,49,50],"thead",{},[51,52,53,57],"tr",{},[54,55,56],"th",{},"輸入或設定",[54,58,59],{},"預期結果",[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},"使用結果前的檢查",[15,106,107,108,113],{},"裝置時鐘不準，目前數值也不準；本頁不使用外部授時服務校準裝置。已保存的數值請到",[109,110,112],"a",{"href":111},"/zh-TW/timestamp-to-date/","時間戳轉日期","選毫秒。程式耗時應用單調時鐘測量，系統校時可能改變日曆時間。",{"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},"複製目前 13 位 Unix 毫秒數，並與秒、微秒和奈秒單位比較。","md","即時精度 / 03",[128,131,134],{"question":129,"answer":130},"目前的毫秒時間戳為什麼通常是 13 位？","現代日期距離 1970 年紀元約有 1.7 兆毫秒，因此正數通常是 13 位；較早或遙遠未來的日期可能不是。",{"question":132,"answer":133},"Date.now() 傳回什麼？","JavaScript Date.now() 傳回裝置時鐘所對應的 Unix 毫秒整數。",{"question":135,"answer":136},"把毫秒乘一百萬就是精確奈秒嗎？","不是。這只能表達奈秒單位，新增的末尾零並非裝置實際量測的次毫秒精度。","zh-TW",{},true,"tool","/zh-tw/milliseconds",null,{"title":144,"description":145},"目前的毫秒時間戳 — 即時 Unix 毫秒數","取得目前 13 位 Unix 毫秒時間戳，並查看秒、微秒、奈秒與安全轉換說明。","zh-TW/milliseconds","HbDqZIIrVUbYLKAa9dv0u1LRvua6ijAw4oDBpPaz_0E",1792032486123]