optional-args

Wraps a function whose last argument is preceded by optional arguments so that when fewer arguments are passed in, missing optional arguments are filled in as undefined.

The is useful for functions that have an API such as (input, options, cb), but the function allows options to be omitted so that it can be called as (input, cb). Rather than having code that examines the arguments to make some optional, just wrap the function with optionalArgs() and it will just work.

install

$ npm install optional-args

example

const optionalArgs = require('optional-args')
 
// 1 optional argument, 3 total arguments
const myFn = optionalArgs(1, 3, (input, options, cb) => {})
 
myFn(123, () => {})
// input === 123
// options === undefined
// typeof cb === 'function'
 
myFn(123)
// input === 123
// options === undefined
// cb === undefined

API

optionalArgs(optionalArgCount, argCount, fn)

• optionalArgCount: number the number of arguments that are optional
• argCount: number the total number of arguments fn accepts
• fn: function the function to be wrapped so that it has optional arguments
• returns: function the wrapped function