fold-args

fold-args

A named-argument parser which also defines a consistent protocol for JavaScript functions.

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:

• if it is not an array object, wrap it by an array object.
• 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 });

• 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],
};

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