fold-args

A named arguments parser with a consistent robust protocol for JavaScript; via folding argumenets in the sense of the computer language Scheme.

Synopsis

function fold_args( 
    args,                 // : array of arguments, 
    default_args,         // : array or an object, 
    transformers_for_args // : array or an object )

If multiple arguments are specified, merge them to a single object

const { fold_args } = require( 'fold-args' );
function func( ...args ) {
  const nargs = fold_args( args );
  console.log( nargs );
}

func( {foo:'FOO'}, {bar:'BAR'} );

> {foo:['FOO'], bar:['BAR']}

It is able to specify a default set of names for named arguments

const { fold_args } = require( 'fold-args' );
function func( ...args ) {
  const nargs = fold_args( args, ['foo','bar'] );
  console.log( nargs );
}

// note that foo and bar are not specified.
func( {bum:'bum'} ); 

// foo and bar are appeared, though. 
> {foo:[],bar:[],bum:['bum']}

It is able to specify precedence for each arguments

const { fold_args } = require( 'fold-args' );
const { the_last }  = require( 'fold-args' );

function func( ...args ) {
  const nargs = fold_args( args, [], [{ foo: the_last }] );
  console.log( nargs );
}

func( {foo:'foo'}, {foo:'FOO'} );

> {foo:'FOO'}

Description

Each value in the arguments are processed in a same manner:

1. if it is not an array object, wrap it by an array object.
2. if it is not an object, convert it to an object as if it is processed by the following code:

(o)=>( typeof o === 'object' ? o : {[Symbol.for(typeof o)] : o });

3. The all objects are merged into an object. For example, if there are two objects like

const o1 = {
  'foo' : 1,
};
const o2 = {
  'bar' : 2,
},

The processed object is

const processed = {
  'foo' : [1],
  'bar' : [2],
};

History

v1.0.0

Relased. (Jan 8 2023)

v1.0.1

Updated README.md. (Jan 8 2023)

v1.0.2

Updated README.md. (Sun, 08 Jan 2023 17:01:38 +0900)

Conclusion

Thank you very much for your attention.

Atsushi Oka / I'm from Tokyo. For further information, see my github account.

Github Repository of fold-args