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• 描述
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

Intl.Locale.prototype.caseFirst property is an accessor property that returns whether case is taken into account for the locale's collation rules.

描述

A locale's collation rules are used to determine how strings are ordered in that locale. Certain locales use a character's case (UPPERCASE or lowercase) in the collation process. This additional rule can be expressed in a Locale's caseFirst 特性。

There are 3 values that the caseFirst property can have, outlined in the table below.

caseFirst 值

Value	描述
upper	Upper case to be sorted before lower case.
lower	Lower case to be sorted before upper case.
false	No special case ordering.

范例

设置 caseFirst value via the locale string

在 Unicode locale string spec , the values that caseFirst represents correspond to the key kf . kf is treated as a locale string "extension subtag". These subtags add additional data about the locale, and are added to locale identifiers by using the -u extension key. Thus, the caseFirst value can be added to the inital locale identifier string that is passed into the Locale constructor. To add the caseFirst value, first add the -u extension key to the string. Next, add the -kf extension key to indicate that you are adding a value for caseFirst . Finally, add the caseFirst value to the string.

let caseFirstStr = new Intl.Locale("fr-Latn-FR-u-kf-upper");
console.log(caseFirstStr.caseFirst); // Prints "upper"
					

Setting the caseFirst value via the configuration object argument

Intl.Locale constructor has an optional configuration object argument, which can be used to pass extension types. Set the caseFirst property of the configuration object to your desired caseFirst value, and then pass it into the constructor.

let caseFirstObj= new Intl.Locale("en-Latn-US", {caseFirst: "lower"});
console.log(us12hour.caseFirst); // Prints "lower"
					

规范

规范
ECMAScript 国际化 API (ECMA-402)

浏览器兼容性

The compatibility table on 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
caseFirst	Chrome 74	Edge 79	Firefox 75	IE No	Opera 62	Safari 14	WebView Android 74	Chrome Android 74	Firefox Android No	Opera Android 53	Safari iOS 14	Samsung Internet Android 11.0	nodejs 12.0.0 12.0.0 Before version 13.0.0, only the locale data for en-US is available by default. See the Locale() 构造函数 了解更多细节。

图例

完整支持

完整支持

不支持

不支持

见实现注意事项。

另请参阅

• Intl.Locale
• Unicode case first collation spec

元数据

• 最后修改： Apr 21, 2020

相关话题

1. 标准内置对象
2. Intl
3. 方法
   1. Intl.getCanonicalLocales()
4. 相关页面：
5. Collator
6. DateTimeFormat
7. ListFormat
8. NumberFormat
9. PluralRules
10. RelativeTimeFormat
11. 继承：
12. Object
13. 特性
    1. Object.prototype.__proto__
    2. Object.prototype.constructor
14. 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()