obvi

Observable state machine. Use pure functions to update state, subscribe to changes with 'observ-struct` interface.

install

$ npm install obvi

example

1var test = require('tape');
2var Store = require('../');
3
4var store = Store({ count: 0 });
5var unsubscribe;
6
7test('obvi', function (t) {
8    t.plan(6);
9
10    var pushEvent = store({
11        add: function (state, event) {
12            t.deepEqual(event, { value: 2 },
13                'should map add event');
14            t.deepEqual(state, { count: 0 }, 'should pass previous state');
15            return { count: state.count + event.value };
16        },
17        increment: function (state, event) {
18            t.deepEqual(event, { type: 'increment' },
19                'should map increment event');
20            t.deepEqual(state, { count: 2 }, 'should update state');
21            return { count: state.count + 1 };
22        }
23    });
24
25    var called = 0;
26    unsubscribe = store.state(function onChange (state) {
27        if (called === 0) {
28            t.deepEqual(state, { count: 2 }, 'should emit new state');
29        }
30        if (called === 1) {
31            t.deepEqual(state, { count: 3 }, 'should emit new state');
32        }
33        called++;
34    });
35
36    pushEvent('add', { value: 2 });
37    pushEvent('increment', { type: 'increment' });
38});
39
40test('events have separate channels', function (t) {
41    t.plan(1);
42    unsubscribe();
43    var push = store({
44        increment: function (state, ev) {
45            return { count: state.count + 10 };
46        }
47    });
48
49    unsubscribe = store.state(function onChange (state) {
50        t.deepEqual(state, { count: 13 },
51            'should handle separate event channels');
52    });
53
54    push('increment')
55});