Intl.Locale.prototype.caseFirst

¥Description

区域设置的排序规则用于确定字符串在该区域设置中的排序方式。某些区域设置在排序过程中使用字符的大小写（大写或小写）。该附加规则可以用 Intl.Locale 对象的 caseFirst 属性来表达。

¥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 Intl.Locale object's caseFirst property.

caseFirst 属性可以有 3 个值，如下表所示。

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

¥caseFirst values

¥Examples

¥Setting the caseFirst value via the locale string

在 Unicode 语言环境字符串规范 中，caseFirst 代表的值对应于键 kf。kf 被视为区域设置字符串 "扩展子标签"。这些子标签添加有关区域设置的附加数据，并使用 -u 扩展键添加到区域设置标识符。因此，可以将 caseFirst 值添加到传递到 Locale 构造函数的初始区域设置标识符字符串中。要添加 caseFirst 值，请首先将 -u 扩展键添加到字符串中。接下来，添加 -kf 扩展键以指示你要添加 caseFirst 的值。最后，将 caseFirst 值添加到字符串中。

¥In the 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 initial 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.

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

¥Setting the caseFirst value via the configuration object argument

Intl.Locale() 构造函数有一个可选的配置对象参数，可用于传递扩展类型。将配置对象的 caseFirst 属性设置为所需的 caseFirst 值，然后将其传递到构造函数中。

¥The 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.

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

¥See also

• Intl.Locale
• Unicode 大小写优先排序规范