Module language

Language tags and ranges.

Provides branded types and utilities for working with BCP 47 language tags (Tag) and RFC 4647 language ranges (TagRange). Use asTag and asTagRange to create validated instances, isTag and isTagRange as type guards, and matchTag to test tags against range patterns.

Language Tags

import { isTag, asTag } from "@metreeca/core";

if (isTag(value)) {
  // value is typed as Tag
}

const languageTag = asTag("en-US");      // US English
const simpleTag = asTag("fr");           // French
const complexTag = asTag("zh-Hans-CN");  // Simplified Chinese (China)
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Language Ranges

import { isTagRange, asTagRange } from "@metreeca/core";

if (isTagRange(value)) {
  // value is typed as TagRange
}

const wildcard = asTagRange("*");       // matches any language
const english = asTagRange("en-*");     // matches any English variant
const swiss = asTagRange("*-CH");       // matches any language in Switzerland
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Matching

import { matchTag, asTag, asTagRange } from "@metreeca/core";

matchTag(asTag("de-CH"), asTagRange("de-*"));  // true - Swiss German matches German range
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