Numbers

Functions for working with numbers.

range(from, to, step=1)

Returns an array of sequential numbers from the starting value, from, up to and including to the end value, to.

range(1, 3);  // [1, 2, 3]

It handles negative numbers correctly, including cases where the range is decreasing in value.

range(-2, 2); // [-2, -1, 0, 1, 2]
range(2, -2); // [2, 1, 0, -1, -2]

An optional third argument can be provided as a stepping value.

range(2, 8, 2);   // [2, 4, 6, 8]
range(-4, 4, 2);  // [-4, -2, 0, 2, 4]
range(4, -4, -2); // [4, 2, 0, -2, -4]

It will also correctly handle the case where you are a numpty and provide a step that has the wrong sign.

range(4, -4, -2); // [4, 2, 0, -2, -4]
range(4, -4, 2);  // [4, 2, 0, -2, -4]

formatNumber(number, options)

This function is for formatting numbers. It is implemented as a wrapper around the Intl.NumberFormat format() function.

The first argument is the number to format. The second optional argument is an object containing configuration options. These can include locale and any of the other options supported by Intl.NumberFormat.

If no options are provided then it will format the number according to the default locale. For my locale (en-GB), the convention is to use commas to separate thousands.

// this works in my locale but might be different in yours
formatNumber(12345); // 12,345

An explicit locale can be provided as a configuration option.

formatNumber(12345, { locale: 'en-GB'});    // 12,345

Other options include style and currency, e.g. for formatting a number as a currency.

formatNumber(12345, { locale: 'en-GB', style: 'currency', currency: 'GBP' })
  // => £12,345.00

currency(number, options)

This is a wrapper around the formatNumber() function for formatting currencies.

currency(12345, { locale: 'en-GB', currency: 'GBP' }) // £12,345.00
currency(12345, { locale: 'en-US', currency: 'USD' }) // $12,345.00

commas(n)

This function will add commas as thousand separators in a number.

commas(12345); // 12,345

An optional second argument can be provided to change the separator.

commas(12345, ' '); // 12 345

For locale-specific number formatting it is recommended that you use formatNumber().

setNumberDefaults(defaults)

This function can be used to set the default options for various number formatting functions.

setNumberDefaults({
  locale: 'en-US',    // default locale
  currency: 'USD',    // default currency
  thousands: ','      // default thousands separator
});

// defaults applied in various functions
numberFormat(12345) // 12,345
currency(12345)     // $12,345.00
commas(12345)       // 12,345

// defaults can be overridden when functions are called
currency(12345, { locale: 'en-GB', currency: 'GBP' }) // £12,345.00