Add a dayPeriod option to Intl.DateTimeFormat() method so the caller can format times such as "7 in the morning", "11 in the morning", "12 noon", "1 in the afternoon", "6 in the evening", "10 at night" (or in Chinese, "清晨7時", "上午11時", "中午12時", "下午1時" ,"下午6時" ,"晚上10時")


This enhances Intl.DateTimeFormat() to match what is already possible in C++ and Java by calling ICU and ICU4J. Without this feature, developers need to either format the quarter in the server or ship a set of day period patterns and hour to day period mappings from the server to client to perform such task.




Specification link

Unknown standards status - check spec link for status

Status in Chromium


Enabled by default (tracking bug)

Consensus & Standardization

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Intent to Prototype url

Intent to Prototype thread


dayPeriod is already part of ECMA402 2021. We should launch this to match the standard. It was set to stage in m78 for more than 1.5 years already.

Search tags

Intl, datetimeformat,

Last updated on 2021-12-20