Number.prototype.toLocaleString()

¥Syntax

toLocaleString()
toLocaleString(locales)
toLocaleString(locales, options)

¥Parameters

locales 和 options 参数自定义函数的行为，并让应用指定应使用其格式约定的语言。

¥The locales and options parameters customize the behavior of the function and let applications specify the language whose formatting conventions should be used.

在支持 Intl.NumberFormat API 的实现中，这些参数与 Intl.NumberFormat() 构造函数的参数完全对应。不支持 Intl.NumberFormat 的实现会被要求忽略这两个参数，从而使所使用的区域设置和返回的字符串形式完全依赖于实现。

¥In implementations that support the Intl.NumberFormat API, these parameters correspond exactly to the Intl.NumberFormat() constructor's parameters. Implementations without Intl.NumberFormat support are asked to ignore both parameters, making the locale used and the form of the string returned entirely implementation-dependent.

locales Optional

带有 BCP 47 语言标记的字符串，或此类字符串的数组。对应于 Intl.NumberFormat() 构造函数的 locales 参数。

在不支持 Intl.NumberFormat 的实现中，该参数被忽略，通常使用主机的区域设置。

options Optional

调整输出格式的对象。对应于 Intl.NumberFormat() 构造函数的 options 参数。

在不支持 Intl.NumberFormat 的实现中，该参数被忽略。

有关这些参数及其使用方法的详细信息，请参阅 Intl.NumberFormat() constructor。

¥See the Intl.NumberFormat() constructor for details on these parameters and how to use them.

¥Return value

根据特定于语言的约定表示给定数字的字符串。

¥A string representing the given number according to language-specific conventions.

在 Intl.NumberFormat 的实现中，这相当于 new Intl.NumberFormat(locales, options).format(number)。

¥In implementations with Intl.NumberFormat, this is equivalent to new Intl.NumberFormat(locales, options).format(number).

注意：大多数时候，toLocaleString() 返回的格式是一致的。但是，即使在同一语言环境中，输出也可能因实现而异 - 输出变化是设计使然，并且规范允许。它也可能不是你所期望的。例如，字符串可以使用不间断空格或被双向控制字符包围。你不应该将 toLocaleString() 的结果与硬编码常量进行比较。

¥Note: Most of the time, the formatting returned by toLocaleString() is consistent. However, the output may vary between implementations, even within the same locale — output variations are by design and allowed by the specification. It may also not be what you expect. For example, the string may use non-breaking spaces or be surrounded by bidirectional control characters. You should not compare the results of toLocaleString() to hardcoded constants.

¥Examples

¥Using toLocaleString()

不指定 locale 的情况下使用此方法的基本用途会返回默认区域设置和默认选项的格式化字符串。

¥Basic use of this method without specifying a locale returns a formatted string in the default locale and with default options.

const number = 3500;

console.log(number.toLocaleString()); // "3,500" if in U.S. English locale

¥Checking for support for locales and options parameters

locales 和 options 参数可能并非在所有实现中都受支持，因为对国际化 API 的支持是可选的，并且某些系统可能没有必要的数据。对于没有国际化支持的实现，toLocaleString() 始终使用系统的区域设置，这可能不是你想要的。因为任何支持 locales 和 options 参数的实现都必须支持 Intl API，因此你可以检查后者是否存在以获取支持：

¥The locales and options parameters may not be supported in all implementations, because support for the internationalization API is optional, and some systems may not have the necessary data. For implementations without internationalization support, toLocaleString() always uses the system's locale, which may not be what you want. Because any implementation that supports the locales and options parameters must support the Intl API, you can check the existence of the latter for support:

function toLocaleStringSupportsLocales() {
  return (
    typeof Intl === "object" &&
    !!Intl &&
    typeof Intl.NumberFormat === "function"
  );
}

¥Using locales

此示例显示本地化数字格式的一些变化。为了获取应用用户界面中使用的语言的格式，请确保使用 locales 参数指定该语言（可能还有一些后备语言）：

¥This example shows some of the variations in localized number formats. In order to get the format of the language used in the user interface of your application, make sure to specify that language (and possibly some fallback languages) using the locales argument:

const number = 123456.789;

// German uses comma as decimal separator and period for thousands
console.log(number.toLocaleString("de-DE"));
// 123.456,789

// Arabic in most Arabic speaking countries uses Eastern Arabic digits
console.log(number.toLocaleString("ar-EG"));
// ١٢٣٤٥٦٫٧٨٩

// India uses thousands/lakh/crore separators
console.log(number.toLocaleString("en-IN"));
// 1,23,456.789

// the nu extension key requests a numbering system, e.g. Chinese decimal
console.log(number.toLocaleString("zh-Hans-CN-u-nu-hanidec"));
// 一二三,四五六.七八九

// when requesting a language that may not be supported, such as
// Balinese, include a fallback language, in this case Indonesian
console.log(number.toLocaleString(["ban", "id"]));
// 123.456,789

¥Using options

可以使用 options 参数自定义 toLocaleString() 提供的结果：

¥The results provided by toLocaleString() can be customized using the options parameter:

const number = 123456.789;

// request a currency format
console.log(
  number.toLocaleString("de-DE", { style: "currency", currency: "EUR" }),
);
// 123.456,79 €

// the Japanese yen doesn't use a minor unit
console.log(
  number.toLocaleString("ja-JP", { style: "currency", currency: "JPY" }),
);
// ￥123,457

// limit to three significant digits
console.log(number.toLocaleString("en-IN", { maximumSignificantDigits: 3 }));
// 1,23,000

// Use the host default language with options for number formatting
const num = 30000.65;
console.log(
  num.toLocaleString(undefined, {
    minimumFractionDigits: 2,
    maximumFractionDigits: 2,
  }),
);
// "30,000.65" where English is the default language, or
// "30.000,65" where German is the default language, or
// "30 000,65" where French is the default language

¥See also

• Intl.NumberFormat
• Number.prototype.toString()