flight-with-state

A Flight mixin for storing and reacting to change in a component's internal state.

Installation

npm install --save flight-with-state

This module requires lodash.merge as a peer dependency.

Example

Here's an example component that uses with withState.

var ToggleButton = flight.component(
    // Use `withState` before your component definition.
    withState,
    function toggleButton() {
        this.attributes({
            initiallyActive: false
        });

        // Define an instance's `initialState`
        this.initialState({
            active: false
        });

        this.after('initialize', function () {
            this.on('click', this.toggle);

            // Track changes to the state using advice
            this.after('stateChanged', this.update);

            // Transition the state using `replaceState`
            this.replaceState({
                active: this.attr.initiallyActive
            });
        });

        this.toggle = function () {
            // Merge changes onto the state using `mergeState`
            this.mergeState({
                // Access the current state using `this.state`
                active: !this.state.active
            });
        };

        this.update = function (state, previousState) {
            this.$node.toggleClass('is-active', state.active);
        };
    }
);

Tracking changes to your state should be done with advice on stateChanged:

this.after('stateChanged', this.reactToStateChange);

API

initialState

initialState, like attributes, takes an object to set up the first state of an instance of a component. If you can pass a function, it will be called at initialize-time to produce the initial value. This allows you to react to the attrs or node of a component to produce the initial state.

For example:

this.initialState({
    active: false,
    id: function () {
        return this.attr.id;
    }
})

Warning: data structures as values in initialState will be shared by instances of a component. If you need a new data structure each time, return it from a function.

replaceState

replaceState changes the component's state to a new value. You can react to a change to state using this.after('replaceState', this.doSomething).

this.replaceState({
    active: false
});
// this.state.active === false
this.replaceState({
    id: '123'
});
// this.state.id === '123'
// this.state.active === undefined

mergeState

mergeState shallow merges an object into the component's state.

this.mergeState({
    active: false
});
// this.state.active === false
this.mergeState({
    id: '123'
});
// this.state.id === '123'
// this.state.active === false

fromState

Make a function that returns the piece of state specified by the key passed.

var getActive = this.fromState('active');
...
getActive.call(this); // returns this.state.active

toState

Make a function that sets the state at key to the value it is called with.

var setActive = this.toState('active');
...
setActive.call(this, false); // sets this.state.active to false

fromAttr

Make a function that returns a components attributes, specified by the key passed.

var id = this.fromAttr('id');
...
id.call(this); // returns this.attr.id

fromAttr is most useful when used with initialState:

this.attributes({
    isActive: false
});

this.initialState({
    active: this.fromAttr('isActive')
});

Development

To develop this module, clone the repository and run:

$ npm install && npm test

If the tests pass, you have a working environment. You shouldn't need any external dependencies.

Contributing to this project

Anyone and everyone is welcome to contribute. Please take a moment to review the guidelines for contributing.

• Bug reports
• Feature requests
• Pull requests