Parse function arguments. Useful to implement variadic functions.
npm install argx --savePass 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 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() |
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)`There are two ways to specify 'or' condition for types.
- Passing string joined by "|" (eg:
args.pop('string|number');) - Passing array as type (eg:
args.pop(['string', MyCustomObj]);)
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.This software is released under the MIT License.