prefer-i18n-service.md

Prefer usage of @salesforce/i18n-service functions over direct use of Intl (prefer-i18n-service)

The direct use of Intl object for formatting date, time and numbers is not recommended in Lightning.

You should be using the @salesforce/i18n-service methods instead.

Usage of following Intl constructor properties is discouraged:

• Intl.DateTimeFormat()
• Intl.NumberFormat()
• Intl.RelativeTimeFormat()

Rule details

Example of incorrect code:

var numberFormatter = new Intl.NumberFormat('de-DE', {
    style: 'currency',
    currency: 'EUR',
});
var dateFormatter = new Intl.DateTimeFormat('fi', {
    year: 'numeric',
    month: 'long',
    day: 'numeric',
});

var formattedNumber = new Intl.NumberFormat('de-DE', {
    style: 'currency',
    currency: 'EUR',
}).format(number);
var formattedDate = new Intl.DateTimeFormat('fi', {
    year: 'numeric',
    month: 'long',
    day: 'numeric',
}).format(date);

Example of correct code:

import { getDateTimeFormat, getNumberFormat } from '@salesforce/i18n-service';

var numberFormatter = getNumberFormat('de-DE', {
    style: 'currency',
    currency: 'EUR',
});
var dateFormatter = getDateTimeFormat('fi', {
    year: 'numeric',
    month: 'long',
    day: 'numeric',
});

var formattedNumber = numberFormatter.format(number);
var formattedDate = dateFormatter.format(date);