Input Amount: Use Cases

Negative Number

It will accept negative numbers with a minus symbol.

export const negativeNumber = () => html`
  <lion-input-amount label="Amount" .modelValue=${-123456.78}></lion-input-amount>
`;

Set currency label

You can optionally set a currency label with the currency attribute, which is visible in the after slot by default.

export const currencySuffix = () => html`
  <lion-input-amount label="Price" currency="USD" .modelValue=${123456.78}></lion-input-amount>
`;

The slot of the currency label can be overwritten by changing the _currencyDisplayNodeSlot protected property, it can be prefix, suffix, before and after.

Force locale

Locale can be forced for a specific lion-input-amount. It will format the amount according to this locale.

export const forceLocale = () => {
  return html`
    <lion-input-amount
      label="Price"
      currency="JOD"
      .locale="nl-NL"
      .modelValue=${123456.78}
    ></lion-input-amount>
  `;
};

The separators are now flipped due to Dutch locale. On top of that, due to JOD currency, the minimum amount of decimals is 3 by default for this currency.

Force digits as input

You can use the preprocessAmount preprocessor to disable users from inputting anything other than digits or separator characters. This is not added by default, but you can add it yourself.

Separator characters include:

• ' ' (space)
• . (dot)
• , (comma)

import { preprocessAmount } from '@lion/ui/input-amount.js';

export const forceDigits = () => html`
  <lion-input-amount label="Amount" .preprocessor=${preprocessAmount}></lion-input-amount>
`;

Faulty prefilled

This example will show the error message by prefilling it with a faulty modelValue.

If there is 1 or more digit in the input, it will ignore invalid characters instead of showing an error feedback message.

export const faultyPrefilled = () => html`
  <lion-input-amount
    label="Amount"
    help-text="Faulty prefilled input will cause error feedback"
    .modelValue=${'foo'}
  ></lion-input-amount>
`;

Modifying the amount of decimals

You can override certain formatting options similar to how you would do this when using Intl NumberFormat. This example shows formatting to whole numbers.

export const noDecimals = () => html`
  <lion-input-amount
    label="Amount"
    help-text="Prefilled and formatted"
    .formatOptions=$
    .modelValue=${20}
  >
  </lion-input-amount>
`;

Paste behavior

For copy pasting numbers into the input-amount, there is slightly different parsing behavior.

Normally, when it receives an input with only 1 separator character, we check the locale to determine whether this character is a group (thousand) separator, or a decimal separator. When a user pastes the input from a different source, we find this approach (locale-based) quite unreliable, because it may have been copied from a 'mathematical context' (like an Excel sheet) or a context with a different locale. Therefore, we use the heuristics based method to parse the input when it is pasted by the user.

What this means

If the user in an English locale types 400,0 it will become 4,000.00 because the locale determines that the comma is a group separator, not a decimal separator.

If the user in an English locale pastes 400,0 instead, it will become 400.00 because we cannot rely on locale. Therefore, instead, we determine that the comma cannot be a group separator because it is not followed by 3 digits after. It is more likely to be a decimal separator.