argx

Parse function arguments. Useful to implement variadic functions.

Installation

npm install argx --save

Usage

Pass the arguments object to .argx() inside your function.

/**
 * This is an example to declare an variadic functions.
 */
'use strict'

const argx = require('argx')

function doSomething (values, options, callback) {
  let args = argx(arguments)
  callback = args.pop('function') || function noop () {} // Consume last argument if it's a function.
  options = args.pop('object') || {} // Consume last argument if it's an object.
  values = args.remain() // Get remaining arguments as array.
  /* ... */
}

doSomething('foo', 'bar')
doSomething('foo', 'bar', { verbose: true })
doSomething('foo', 'bar', (err) => {})
doSomething('foo', 'bar', { verbose: true }, (err) => {})

API Guide

API guide for Argx instance, which is returned by argx(arguments).

| Signature | Description | Example | ----- | ----- | --- | | .pop() | Pop an argument value from last. | args.pop() | | .pop(count) | Pop multiple values from last. Orders are preserved. | args.pop(1) | | .pop(type) | Pop only if the last value conform the type. | args.pop("number") args.pop("number|string") args.pop(CustomObj) | | .pop(count, type) | Pop values while conforming the type. | args.pop(2, "number") args.pop(1, CustomObj) | | .shift() | Shift an argument value from top. | args.shift() | | .shift(count) | Shift multiple values from top. | args.shift(2) | | .shift(type) | Shift only if the top value conform the type. | args.shift("string") args.pop("object|string") args.shift(CustomObj) | | .shift(count, type) | Shift values while conforming the type. | args.shift(2, "string") args.shift(4, CustomObj) | | .remain() | Shift all remained values. Always returns an array. | args.remain() |

Tips

Detecting Custom Types.

Type which .pop()/.shift() accept is string, a custom object or a custom constructor.

function MyConstructor(){/*...*/};
args.pop(MyConstructor); // Pop only if the last argument is instantiate by `new MyConstructor()`

var MyObj = {/*...*/};
args.pop(MyObj); // Pop only if the last argument is create by `Object.create(MyObj)`

Specify Multiple Types

There are two ways to specify 'or' condition for types.

1. Passing string joined by "|" (eg: args.pop('string|number'); )
2. Passing array as type (eg: args.pop(['string', MyCustomObj]); )

Want Array Always

Note that .pop()/.shift() methods returns values as array only when multiple entries hit. If you want to make sure to keep values as array, use [].concat().

var args = argx(arguments);
var values = [].concat(args.pop(2, 'string') || []); // Always array.

License

This software is released under the MIT License.