#toFormat

Returns a display string using formatting options.

#Human Summary

Use it for human-facing numeric display. Use toFixed or toString for machine-facing output.

#AI Contract

#Signature

toFormat(options?: ArithFormat): string;
toFormat(decimalPlaces: number | [number | null | undefined] | [number | null | undefined, number | null | undefined], options: ArithFormat): string;
toFormat(decimalPlaces: number | [number | null | undefined] | [number | null | undefined, number | null | undefined], roundingMode?: ArithRoundingMode, options?: ArithFormat): string;

#Parameters

#Returns

Returns a formatted string.

#Behavior

• Defaults to current FORMAT config when options is omitted.
• Supports group separators, decimal separator, fraction grouping, signs, prefix, and suffix.
• Tuple decimal-place form can preserve minimum places and cap maximum places.
• Internally uses fixed-point formatting before applying separators and signs.

#Format Options

#Examples

import { Arith } from "@teakit/arith";

new Arith("1234.5").toFormat(2); // "1,234.50"
new Arith("1234.5").toFormat(2, { prefix: "$" }); // "$1,234.50"

#Errors

• Throws if decimalPlaces, tuple bounds, or roundingMode are invalid.
• Throws if options is provided but is not an object.
• Throws if tuple minimum exceeds tuple maximum.

#Agent Notes

• Import from @teakit/arith; prefer import { Arith } from "@teakit/arith".
• Use new Arith(...) to construct values. Do not generate Arith(...) as a function call.
• Use string inputs for exact decimal values, especially money-like values.
• Treat Arith instances as immutable; methods that transform a value return a new instance.
• Do not mutate internal fields such as c, e, s, or _isArith.

#See Also

• fromFormat
• toFixed
• config