mithril-proptypes

Awesome lightweight library for data validation and type checking for Mithril.js inspired by React PropTypes. You can use this library as a standalone dependency, because it doesn't have a binding with Mithril.js, though provides special tools to easy integration with Mitril.

Basic Usage

```js import { PropTypes, checkProps } from 'mithril-proptypes';

const propTypes = { id: PropTypes.number.isRequired, name: PropTypes.string, done: PropTypes.boolean, };

const props = { id: 1, name: 'Dmitry Salnikov', done: 'false' };

checkProps(props)(propTypes);

// WARN >> PropTypes warning: Wrong prop type for "done": "string" instead of declared "boolean"

<h2>With ES6 classes</h2>
If you use es6 classes for mithril components, then you can do the check in the constructor for example:
```js
import { PropTypes, checkProps } from 'mithril-proptypes';

const propTypes = {
  id: PropTypes.number.isRequired,
  name: PropTypes.string,
  done: PropTypes.boolean,
};

class TodoItem {
  constructor(props) {
    checkProps(props)(propTypes);
    
    this.props = props;
  }
  
  view() {
    return (
      <div className="TodoItem">{this.props.name}</div>
    );
  }
}

MithrilComponent class

To simplify usage of such checks in the every your mithril component you can extend from the MithrilComponent class provided by this library: ```js import { MithrilComponent, PropTypes } from 'mithril-proptypes';

const propTypes = { id: PropTypes.number.isRequired, name: PropTypes.string, done: PropTypes.boolean, };

class TodoItem extends MithrilComponent { constructor(props) { super(props, propTypes); }

view() { return (

{this.props.name}

); } }

Now this check is doing by MithrilComponent.

<h2>defaultProps with MithrilComponent</h2>
If your data doesn't contain some property but you define default value for it with 'defaultProps' - then it will be automatically replaced with that value.
```js
import { MithrilComponent, PropTypes } from 'mithril-proptypes';

const propTypes = {
  id: PropTypes.number.isRequired,
  name: PropTypes.string,
  done: PropTypes.boolean,
};

const defaultProps = {
  done: false,
};

class TodoItem extends MithrilComponent {
  constructor(props) {
    super(props, propTypes, defaultProps);
  }
  
  view() {
    return (
      <div className="TodoItem">{this.props.done}</div>
    );
  }
}

Additional features of MithrilComponent

MithrilComponent class also adds useful lifecycle method onUnload() to your component. This method will be called by mithril.js when this component is going to be removed from the DOM, so you can save some data for example. ```js import { MithrilComponent, PropTypes } from 'mithril-proptypes';

class App extends MithrilComponent { constructor(props) { super(); }

onUnload() { console.log('Component is going to be removed from the DOM'); }

view() { return

; } }

<h2>Available Types</h2>
PropTypes:
* string
* number
* boolean
* function
* object
* array
* objectWith() - complex type
* arrayOf() - complex type

<h2>Complex Types</h2>
objectWith - is a type definition of each property of an object
arrayOf - is a type definition of each item of an array (each  property of object-item)
```js
var props = {
    someObject: {
        first: 13,
        second: 'second',
        third: true
    },
    someArray: [
        {
            id: 1,
            gender: 'male',
            married: false
        },
        {
            id: '2',
            gender: 'female',
            married: true
        },
        {
            id: 3,
            gender: 'male',
            married: false
        }
    ],
};

var propTypes = {
    someObject: PropTypes.objectWith({
        first: PropTypes.number,
        second: PropTypes.string,
        third: PropTypes.boolean,
    }),
    someArray: PropTypes.arrayOf({
        id: PropTypes.number,
        gender: PropTypes.string,
        married: PropTypes.boolean,
    }).isRequired,
};

Required Props

Is some property is 'required' by the data doesn't contain this property - then check will print error. To mark some prop as required you can add '.isRequired' to each prop type: ```js var props = {};

var propTypes = { someProp: PropTypes.number.isRequired, };

checkProps(props)(propTypes); // ERROR >> PropTypes warning: data for the required prop someProp is absent!

<h2>Install</h2>

At first - <a href="https://nodejs.org/en/download/">download and install Node.js</a> if you need. It contains own package-manager - NPM.
Then run npm to install all necessary dependencies

```shell
npm install mithril-proptypes --save

Use with Node.js

```js var checkProps = require('mithril-proptypes').checkProps;

// ...

checkProps(props)(proptypes);

<h2>Planned Features</h2>
* Turn off checks for production
* ArrayOf can describe not only objects, it can be array of numbers, strings or any other type.
* Custom validators