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MessageFormatClassic

Open Beta Documentation Amazon offers this technical documentation as part of a pre-release, open beta. The features described might change as Amazon receives feedback and iterates on the features. For the most current feature information, see the Release Notes.

Classdesc

MessageFormatClassic class accepts the classic ICU MessageFormat patterns for formatting messages.

MessageFormatClassic supports both named-argument style and numbered-argument style in patterns. Named-argument style is recommended because with descriptively named arguments, both developers and translators benefit from improved readability and can better infer what kind of values go into arguments in a pattern.

Examples

import { MessageFormatClassic } from '@amazon-devices/keplerscript-kepleri18n-lib';
...
    // Pattern should be retrieved from string resources. It's hardcoded here for brevity of example only.
    const pattern: string = "Car number {carNumber} wins! Congratulations, {driverName}!";
    const carNumber: number = 3;
    const driverName: string = "Alice";
    const argMap = new Map<string, number | string | Date>();
    argMap.set("carNumber", carNumber);
    argMap.set("driverName", driverName);
    const message: string | null = MessageFormatClassic.format(pattern, argMap);
    if (message === null) {
        // Error
        return;
    }
    // message is "Car number 3 wins! Congratulations, Alice!".

import { MessageFormatClassic } from '@amazon-devices/keplerscript-kepleri18n-lib';
...
    // Pattern should be retrieved from string resources. It's hardcoded here for brevity of example only.
    const pattern: string = "Car number {0} wins! Congratulations, {1}!";
    const carNumber: number = 11;
    const driverName: string = "Bob";
    const message: string | null = MessageFormatClassic.formatPositional(pattern, carNumber, driverName);
    if (message === null) {
        // Error
        return;
    }
    // message is "Car number 11 wins! Congratulations, Bob!".

Constructors

new MessageFormatClassic()

new MessageFormatClassic(): MessageFormatClassic

Returns

MessageFormatClassic

Methods

format()

static format(pattern, args): null | string

Formats given pattern with named arguments in default Locale.

Parameters

pattern

string

A classic message format pattern.

args

Map<string, string | number | Date>

Map of argument names to their values.

Returns

null | string

Formatted message on success, null on failure.

formatPositional()

static formatPositional(pattern, …args): null | string

Formats given pattern with numbered arguments in default Locale.

Parameters

pattern

string

A classic message format pattern.

args

…(string | number | Date)[]

Array of argument values

Returns

null | string

Formatted message on success, null on failure.

formatPositionalWithLocale()

static formatPositionalWithLocale(pattern, locale, …args): null | string

Formats given pattern with numbered arguments in given locale.

Parameters

pattern

string

A classic message format pattern.

locale

A BCP-47 locale string. If this parameter is null or empty string, default locale is used.

null string

args

…(string | number | Date)[]

Array of argument values

Returns

null | string

Formatted message on success, null on failure.

formatWithLocale()

static formatWithLocale(pattern, locale, args): null | string

Formats given pattern with named arguments in given Locale.

Parameters

pattern

string

A classic message format pattern.

locale

A BCP-47 locale string. If this parameter is null or empty string, default locale is used.

null string

args

Map<string, string | number | Date>

Map of argument names to their values.

Returns

null | string

Formatted message on success, null on failure.

getMajorVersion()

static getMajorVersion(): number

Gets major version number.

Returns

number

Major version number.

getMinorVersion()

static getMinorVersion(): number

Gets minor version number.

Returns

number

Minor version number.

getPatchVersion()

static getPatchVersion(): number

Gets patch version number.

Returns

number

Patch version number.

Last updated: Sep 30, 2025