检测国际化支持

要验证是否启用了 ICU（system-icu、small-icu 或 full-icu），只需检查 Intl 是否存在就足够了：

const hasICU = typeof Intl === 'object';

或者，检查 process.versions.icu，一个仅在启用 ICU 时定义的属性，也可以工作：

const hasICU = typeof process.versions.icu === 'string';

要检查对非英语语言环境（即 full-icu 或 system-icu）的支持，Intl.DateTimeFormat 可能是一个很好的区分因素：

const hasFullICU = (() => {
  try {
    const january = new Date(9e8);
    const spanish = new Intl.DateTimeFormat('es', { month: 'long' });
    return spanish.format(january) === 'enero';
  } catch (err) {
    return false;
  }
})();

有关 Intl 支持的更详细的测试，以下资源可能会有所帮助：

• btest402: 一般用于检查是否正确地构建了支持 Intl 的 Node.js。
• Test262: ECMAScript 的官方一致性测试套件包括一个专门针对 ECMA-402 的部分。

To verify that ICU is enabled at all (system-icu, small-icu, or full-icu), simply checking the existence of Intl should suffice:

const hasICU = typeof Intl === 'object';

Alternatively, checking for process.versions.icu, a property defined only when ICU is enabled, works too:

const hasICU = typeof process.versions.icu === 'string';

To check for support for a non-English locale (i.e. full-icu or system-icu), Intl.DateTimeFormat can be a good distinguishing factor:

const hasFullICU = (() => {
  try {
    const january = new Date(9e8);
    const spanish = new Intl.DateTimeFormat('es', { month: 'long' });
    return spanish.format(january) === 'enero';
  } catch (err) {
    return false;
  }
})();

For more verbose tests for Intl support, the following resources may be found to be helpful:

• btest402: Generally used to check whether Node.js with Intl support is built correctly.
• Test262: ECMAScript's official conformance test suite includes a section dedicated to ECMA-402.