Function applyNumberFormatting

src/helpers.js:225–270

(
	value,
	locale,
	localeOptions,
	separator,
	pad,
	round,
	roundingFunc,
)

 * @returns {string|number} Formatted value
 */
export function applyNumberFormatting(
	value,
	locale,
	localeOptions,
	separator,
	pad,
	round,
	roundingFunc,
) {
	let result = value;

	// When padding alongside a locale, let the locale formatter emit the fixed
	// number of fraction digits. The manual string padding below cannot tell a
	// locale-inserted grouping separator from the decimal separator, so it
	// dropped digits (e.g. "1,234,500" became "1,234").
	const localePad =
		pad && round > 0 ? { minimumFractionDigits: round, maximumFractionDigits: round } : undefined;

	// Apply locale formatting
	if (locale === true) {
		result = result.toLocaleString(undefined, localePad);
	} else if (locale.length > 0) {
		result = result.toLocaleString(locale, { ...localeOptions, ...localePad });
	} else if (separator.length > 0) {
		// Round before separator replacement to ensure excess decimal places
		// are truncated when pad is also set (fixes padding + separator bug).
		if (pad && round > 0) {
			const p = Math.pow(10, round);
			result = roundingFunc(result * p) / p;
		}
		result = result.toString().replace(PERIOD, separator);
	}

	// Apply padding for the non-locale paths, where the string has a single
	// decimal separator and no grouping is inserted.
	if (pad && round > 0 && locale !== true && locale.length === 0) {
		const resultStr = result.toString();
		const x = separator || PERIOD;
		const tmp = resultStr.split(x);
		const s = tmp[1] || EMPTY;

		result = `${tmp[0]}${x}${s.padEnd(round, ZERO)}`;
	}

	return result;
}

/**
 * Calculates exponent from the input value using pre-computed log values and clamps to supported range