Continu 🐯

Continu is a powerful tool for managing key-value pairs in an application. Its simple and lightweight design makes it easy to use. Besides, defining default values it is also possible to execute transformations & validations before setting any value.

Table of Contents

• Installation
• Usage
  • Basic
  • Defaults
  • Transformation
  • Validation
  • Nesting
  • Getters
• Contributing
• License

Installation

npm install continu --save

Usage

Basic

On the basic level, this library can be used as container for arbitrary key value pairs.

import { Continu } from 'continu';

type Options = {
    foo: string
}

const continu = new Continu<Options>();

console.log(continu.has('foo'));
// false
console.log(continu.get('foo'));
// undefined

continu.set('foo', 'bar');

console.log(continu.has('foo'));
// true
console.log(continu.get('foo'));
// bar

continu.reset('foo');

console.log(continu.has('foo'));
// false

Defaults

It is also possible to define default values which are returned if a given value is not set.

import { Continu } from 'continu';

type Options = {
    foo: string
}

const continu = new Continu<Options>({
    defaults: {
        foo: 'bar'
    }
});

console.log(continu.has('foo'));
// false
console.log(continu.get('foo'));
// 'bar'

continu.set('foo', 'baz');

console.log(continu.has('foo'));
// true
console.log(continu.get('foo'));
// 'baz'

Transformation

Transformers can be used to accept multiple input formats. The data can than be converted to the appropriate format before setting. Therefore, the setRaw method must be used.

import { Continu } from 'continu';

type Options = {
    foo: string
}

const continu = new Continu<Options>({
    transformers: {
        foo: (value) => {
            if(typeof value === 'number') {
                return `${value}`;
            }

            if(typeof value === 'string') {
                return value;
            }

            throw new Error('Option could not be transformed.')
        }
    }
});

continu.set('foo', '123');

console.log(continu.get('foo'));
// '123'

continu.set('foo', 456);

console.log(continu.get('foo'));
// '456'

continu.set('foo', {bar: 'baz'});
// this statement will throw an error!

Validation

Validators can be useful for defining constraints and prevent values from being set, if they don't match specific criteria.

import { Continu } from 'continu';

type Options = {
    foo: string
}

const continu = new Continu<Options>({
    validators: {
        foo: (value) => typeof value === 'string' && value.length > 3,
    }
});

continu.set('foo', 'bar');

console.log(continu.get('foo'));
// undefined

continu.set('foo', 'bar-baz');

console.log(continu.get('foo'));
// 'bar-baz'

Nesting

When using nested object types, it is also possible to use key paths (separated by .) to access properties in depth.

import { Continu } from 'continu';

type Options = {
    nested: {
        foo: string
    }
}

const continu = new Continu<Options>();

console.log(continu.has('nested.foo'));
// false
console.log(continu.get('nested.foo'));
// undefined

continu.set('nested.foo', 'bar');

console.log(continu.has('nested.foo'));
// true
console.log(continu.get('nested.foo'));
// 'bar'

console.log(continu.has('nested'));
// true;
console.log(continu.get('nested'));
// { foo: 'bar' }

Getters

It is also possible to define dynamic getters for specific key (paths).

import { Continu } from 'continu';

type Options = {
    foo: string,
    nested: {
        baz: string
    }
}

const continu = new Continu<Options>({
    defaults: {
        foo: 'bar'
    },
    getters: {
        nested: (context) => {
            return {
                baz: context.getDefault('foo')
            }
        }
    }
});

// always evaluates to false,
// since a key path may not be accessible until a getter has been evaluated.
console.log(continu.has('nested'));

console.log(continu.get('nested'));
// { foo: 'bar' }

console.log(continu.get('nested.baz'));
// 'bar'

Contributing

Before starting to work on a pull request, it is important to review the guidelines for contributing and the code of conduct. These guidelines will help to ensure that contributions are made effectively and are accepted.

License

Made with 💚

Published under MIT License.