halis-state/src/state.js

Manage immutable state with these helpers for Objects and Arrays

'use strict';

const isObject = object => {
	if ( object instanceof Array ) return false;
	else if ( object === null ) return false;
	else return typeof object === 'object';
};
const isArray = array => array instanceof Array;
const isString = string => typeof string === 'string';

const defaultFn = ( is, defaultValue ) => {
	return object => {
		if ( object && is( object) ) return object;
		else return defaultValue;
	};
};

const defaultObject =  defaultFn( isObject, {} );
const defaultArray = defaultFn( isArray, [] );

const copyObject = ( object, merge ) => {
	merge = defaultObject( merge || {} );
	object = defaultObject( object || {} );

	return Object.assign( merge, object );
};

const copyArray = ( array, merge ) => ( array || [] ).concat( merge || [] );

const insertObject = ( object, key, value ) => {
	let copy;

	if ( !key || !isString( key ) ) return object;

	copy = copyObject( object );
	copy[ key ] = value || null;

	return copy;
};

const pushArray = ( array, item ) => {
	let copy;

	if ( !array || !array.length || !isArray( array ) ) return [ item ];
	if ( item === undefined ) return array;

	copy = copyArray( array );
	copy.push( item );

	return copy;
};

const removeArrayIndex = ( array, index ) => {
	let copy;

	if ( !array || array.length < index ) return array;

	copy = copyArray( array );
	copy.splice( index, 1 );

	return copy;
};

const removeObjectKey = ( object, key ) => {
	let copy;

	if ( !key || !isString( key ) || object[ key ] === undefined ) return object;

	copy = copyObject( object );

	delete copy[ key ];

	return copy;
};

module.exports = {
	isObject,
	isArray,
	isString,
	defaultObject,
	defaultArray,
	copyObject,
	copyArray,
	insertObject,
	pushArray,
	removeArrayIndex,
	removeObjectKey
};