The Array type represents a list of values. The values in an array can be of any other type supported by Sywac.


In addition to common type properties, arrays also support:

  •  delimiter or delim: string or RegExp, default ','

    A delimiter used to split a single value into multiple values during parsing.

    For example, parsing -a one,two would add values 'one' and 'two' to the array instead of 'one,two'.

  •  cumulative: boolean, default true

    If a flag is given multiple times, should the array value include all values from all flags (default) or only use the value(s) from the last flag given?

    For example, parsing -a one two -a three four in cumulative mode would result in an array value of ['one', 'two', 'three', 'four']. If you turn this off, the result would be only ['three', 'four'].


Use the .array method to add a flagged option for an array of strings.

  .array('--people', { desc: 'specify a list of people' })
  .parseAndExit().then(argv => {
    console.log(`Welcome ${argv.people.join(', ')}!`)
$ my-app --people Anna George Stefan
Welcome Anna, George, Stefan!

The default value for an Array is [].

$ my-app
Welcome !

The .stringArray method is a more explicit alias for .array.

  .stringArray('--people', { desc: 'specify a list of people' })

Use the .numberArray method to add a flagged option for an array of numbers.

  .numberArray('--max <numbers...>', { desc: 'specify a list of numbers' })
  .parseAndExit().then(argv => {
$ my-app 5 19 2

To define an array of any other type, use the .option method and specifying the array type. The properties of your array can include properties supported by the array type. (For example, if you specify a type of array:file, you can also add properties related to the File type.)

  .option('--f <files...>', { type: 'array:file', mustExist: true })
$ my-app -f file1 file2
Usage: my-app [options]

  --f                                                            [array:file] [must exist]

The file does not exist: file1
The file does not exist: file2

Use the .positional method to define a positional argument array.

  .parseAndExit().then(argv => {
    console.log(`Welcome ${argv.names.join(', ')}!`)
$ my-app April Steve Jo
Welcome April, Steve, Jo!

When parsing positional arguments, an array type will do its best to leave enough arguments to satisfy other defined arguments. If the arguments are ambiguous (such as multiple arrays in a row), your users should use a value with delimiters instead of spaces.

  .positional('<names...> <foods...>')
  .parseAndExit().then(argv => {
    console.log(`Welcome ${argv.names.join(', ')}!`)
    console.log(`I like to eat ${argv.foods.join(', ')}!`)
$ my-app April,Steve fruits,veggies
Welcome April, Steve!
I like to eat fruits, veggies!

$ my-app April Steve fruits veggies
Welcome April, Steve, fruits!
I like to eat veggies!