/**
 * Formats a number with locale-aware thousands separators.
 *
 * Uses a fixed 'en-US' locale for deterministic output. Returns '--' for
 * non-finite values (NaN, Infinity, null, undefined).
 *
 * @param value - The number to format (accepts null/undefined)
 * @returns Formatted string with thousands separators, e.g. "1,234,567"
 *
 * @example
 * formatNumber(1234567)   // "1,234,567"
 * formatNumber(0)         // "0"
 * formatNumber(-42)       // "-42"
 * formatNumber(NaN)       // "--"
 * formatNumber(null)      // "--"
 */
export declare function formatNumber(value: number | null | undefined): string;
/**
 * Formats a number in compact abbreviated form.
 *
 * Numbers below 1,000 (in absolute value) are returned as-is with locale formatting.
 * Larger numbers are abbreviated with K, M, B, or T suffixes with one decimal place.
 * Returns '--' for non-finite values (NaN, Infinity, null, undefined).
 *
 * @param value - The number to format (accepts null/undefined)
 * @returns Abbreviated string, e.g. "1.2M", "1.5K", "999"
 *
 * @example
 * formatCompact(1234567)  // "1.2M"
 * formatCompact(1500)     // "1.5K"
 * formatCompact(999)      // "999"
 * formatCompact(-2500)    // "-2.5K"
 * formatCompact(0)        // "0"
 * formatCompact(NaN)      // "--"
 */
export declare function formatCompact(value: number | null | undefined): string;
/**
 * Formats a ratio as a percentage string with configurable precision.
 *
 * Computes `(numerator / total) * 100` and formats with the specified decimal places.
 * Returns '--' for non-finite inputs or when total is zero (division by zero).
 *
 * @param numerator - The numerator value (accepts null/undefined)
 * @param total - The total/denominator value (accepts null/undefined)
 * @param precision - Number of decimal places (default: 1)
 * @returns Formatted percentage string, e.g. "45.0%"
 *
 * @example
 * formatPercent(45, 100)      // "45.0%"
 * formatPercent(1, 3, 2)      // "33.33%"
 * formatPercent(0, 100)       // "0.0%"
 * formatPercent(45, 0)        // "--"
 * formatPercent(NaN, 100)     // "--"
 */
export declare function formatPercent(numerator: number | null | undefined, total: number | null | undefined, precision?: number): string;
/**
 * Formats a byte count as a human-readable size string.
 *
 * Uses binary (IEC) units: KB = 1024, MB = 1024^2, etc.
 * Returns '--' for non-finite or negative values. Returns "0 B" for zero.
 *
 * @param value - The byte count to format (accepts null/undefined)
 * @returns Human-readable byte string, e.g. "1.0 MB", "512 B"
 *
 * @example
 * formatBytes(1048576)    // "1.0 MB"
 * formatBytes(1536)       // "1.5 KB"
 * formatBytes(500)        // "500 B"
 * formatBytes(0)          // "0 B"
 * formatBytes(-1)         // "--"
 * formatBytes(NaN)        // "--"
 */
export declare function formatBytes(value: number | null | undefined): string;