SagUI

Money input

A currency field with live grouping, stable width, rolling digits, and minor-unit output.

import { MoneyInput } from "@sagui/ui";
Markdown
Loading demo

When to use

  • Payment, tip, transfer, or budget amounts entered by hand.
  • Invoice and expense forms where the currency may change.
  • Amount fields that benefit from quick add chips such as +$10.

When not to use

  • Use number-field for quantities and non currency numbers.
  • Use slider or price-ladder when people pick from a range rather than type.
  • Use scrub-input for design tool style drag adjustments.

Installation

Install the package and import the styles once. The installation guide covers the Tailwind setup.

$ npm install @sagui/ui

Usage

example.tsx
import { useState } from "react";
import { MoneyInput } from "@sagui/ui";

export function TipAmount() {
  const [cents, setCents] = useState<number | null>(1500);
  return (
    <MoneyInput
      label="Amount"
      name="amount"
      value={cents}
      onValueChange={setCents}
      currencies={["USD"]}
      min={100}
      max={100_000}
      quickAdd={[5, 10, 20]}
    />
  );
}

Examples

Reading the value

The value comes out in minor units, so $12.50 is 1250.

Loading demo

Limits

Typing past max is refused with a nudge. A value under min is reported when the field loses focus.

Loading demo

Other currencies and locales

Grouping, the decimal mark and the symbol position follow the locale and currency.

Loading demo

Currencies without minor units, such as yen, have no cents.

Loading demo

API reference

MoneyInput

A currency amount field that groups digits as you type, holds missing cents as ghosts, scales long amounts to fit, and returns minor units.

Prop Type Default Description
label (required) string – Field label.
hideLabel boolean false Keeps the label for screen readers only.
value number | null – Controlled amount in minor units (cents for USD, yen for JPY). null is empty.
defaultValue number | null null Starting amount in minor units when uncontrolled.
onValueChange (value: number | null, details: MoneyInputDetails) => void – Called with minor units and { currency, major, formatted }.
currency string – Controlled ISO 4217 code, such as "USD".
defaultCurrency string "USD" Starting currency when uncontrolled.
onCurrencyChange (currency: string) => void – Called when a currency is picked. The major amount carries over.
currencies string[] ["USD", "EUR", "GBP", "JPY", "CAD", "AUD", "CHF", "INR"] Codes in the currency menu. Pass one code to hide the menu.
min number – Lowest amount in minor units. Checked when the field loses focus.
max number – Highest amount in minor units. Typing past it is refused with a nudge.
quickAdd number[] [10, 50, 100] Quick add chips in major units. Pass an empty array to hide them.
step number – Arrow keys move by this many minor units. Defaults to one major unit; Shift moves ten times as far.
locale string "en-US" Formatting locale. Fixed by default so server and client render the same digits.
description string – Hint under the field.
error string – Replaces the built-in range message.
disabled boolean false Disables the field, menu, and chips.
name string – Adds a hidden input carrying the amount in minor units.
id string – Id of the input.
className string – Class on the root.
onBlur (event: FocusEvent<HTMLInputElement>) => void – Called when the input loses focus, after the fraction settles.
ref Ref<HTMLInputElement> – Forwarded to the input.

Keyboard interactions

Keys Action
ArrowUporArrowDown Adds or subtracts one step (one major unit by default).
Shift+ArrowUporShift+ArrowDown Moves ten steps.
PageUporPageDown Moves ten steps.
Enter Settles the fraction, such as 12.5 to 12.50.
BackspaceorDelete Over a group separator, deletes the digit beside it.
ArrowDownorArrowUpon the currency button Opens the currency menu.
ArrowDownorArrowUporHomeorEndin the menu Moves through currencies; typing jumps by code or name.
EnterorSpacein the menu Picks the highlighted currency.
Escapein the menu Closes the menu and returns to the button.

Accessibility

  • The input has role="spinbutton" with aria-valuenow in major units, aria-valuetext as the full currency string, and min and max when set.
  • The animated digits are aria-hidden; the real input carries the value, so screen readers and autofill see plain text.
  • The range, hint, and error are linked with aria-describedby; limits, chip adds, and currency changes are announced politely.
  • The currency menu is a listbox with aria-activedescendant and typeahead.

Motion

  • Chips and arrow keys roll each digit column in the direction of change while new columns open their width; typing cuts straight to the result so the caret never lags.
  • A refused change kicks the amount sideways on a bouncy spring and flashes the range.
  • The currency symbol swaps with a short roll while its slot springs to the new width; long amounts scale down to fit on a spring.
  • Reduced motion removes the rolls, kick, and width springs; digits fade and sizes jump.

Responsive behavior

  • Under 420px viewport width the amount text drops a size and the padding tightens.
  • A ResizeObserver scales the amount down to fit its box instead of scrolling, so long numbers stay readable on phones.
  • inputMode is decimal (numeric for zero decimal currencies like JPY), which brings up the number keypad on touch.

Performance

  • Intl.NumberFormat instances are cached per locale and currency.
  • Each digit is its own animated column; amounts are capped at 12 integer digits, which keeps the column count small.

Notes

  • Store the value in minor units (integers) to avoid floating point errors; details.major and details.formatted are for display.
  • Use for money only. For plain numbers with units use number-field, and for drag-to-adjust values use scrub-input.
  • Pass one code in currencies to lock the currency; the code then shows as static text.
  • max refuses typing past it; min is only checked on blur, so people can type through smaller amounts on the way.

Also in special inputs