commit 实现
总述：
- 解构对于的参数，确保能准确的拿到参数
- 去mutations找对应的Fn，找到就保存下来，找不到就直接返回
- 通过 _withCommit 方法能保证找到正确的mutations里面的Fn，需要遍历执行
- 执行收集的 subscribe 的所有方法
/**
* store.commit 方法
* 最终还是执行 mutation 方法
* @param {String} _type 方法名
* @param {Object} _payload 参数
* @param {Object} _options
*/
commit (_type, _payload, _options) {
// 解构 传进来的参数
const {
type,
payload,
} = unifyObjectStyle(_type, _payload, _options)
// 保存 state payload
const mutation = { type, payload }
// 找到对应的 mutations => [addFn,addFn,...]
const entry = this._mutations[type]
// 没找到就直接返回
if (!entry) return
// 保证此处修改是符合规则的
this._withCommit(() => {
// 遍历 mutation 数组执行里面的 commit 方法
entry.forEach(function commitIterator (handler) {
handler(payload)
})
})
// 执行收集的 subscribe 的所有方法
this._subscribers
.slice()
.forEach(sub => sub(mutation, this.state))
}
dispatch 实现
dispatch (_type, _payload) {
const {
type,
payload
} = unifyObjectStyle(_type, _payload)
const action = { type, payload }
const entry = this._actions[type]
if (!entry) return
try {
this._actionSubscribers
.slice()
.filter(sub => sub.before)
.forEach(sub => sub.before(action, this.state))
} catch (e) {
}
const result = entry.length > 1
? Promise.all(entry.map(handler => handler(payload)))
: entry[0](payload)
return new Promise((resolve, reject) => {
result.then(res => {
try {
this._actionSubscribers
.filter(sub => sub.after)
.forEach(sub => sub.after(action, this.state))
} catch (e) {
}
resolve(res)
}, error => {
try {
this._actionSubscribers
.filter(sub => sub.error)
.forEach(sub => sub.error(action, this.state, error))
} catch (e) {
}
reject(error)
})
})
}
