forked from xieranmaya/Promise3
-
Notifications
You must be signed in to change notification settings - Fork 1
/
Promise3.js
258 lines (230 loc) · 6.92 KB
/
Promise3.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
var Promise = (function() {
function Promise(resolver) {
if (typeof resolver !== 'function') {
throw new TypeError('Promise resolver ' + resolver + ' is not a function')
}
if (!(this instanceof Promise)) return new Promise(resolver)
var self = this
self.callbacks = []
self.status = 'pending'
function resolve(value) {
setTimeout(function() {
if (self.status !== 'pending') {
return
}
self.status = 'resolved'
self.data = value
for (var i = 0; i < self.callbacks.length; i++) {
self.callbacks[i].onResolved(value)
}
})
}
function reject(reason) {
setTimeout(function(){
if (self.status !== 'pending') {
return
}
self.status = 'rejected'
self.data = reason
for (var i = 0; i < self.callbacks.length; i++) {
self.callbacks[i].onRejected(reason)
}
})
}
try{
resolver(resolve, reject)
} catch(e) {
reject(e)
}
}
function resolvePromise(promise, x, resolve, reject) {
var then
var thenCalledOrThrow = false
if (promise === x) {
return reject(new TypeError('Chaining cycle detected for promise!'))
}
if ((x !== null) && ((typeof x === 'object') || (typeof x === 'function'))) {
try {
then = x.then
if (typeof then === 'function') {
then.call(x, function rs(y) {
if (thenCalledOrThrow) return
thenCalledOrThrow = true
return resolvePromise(promise, y, resolve, reject)
}, function rj(r) {
if (thenCalledOrThrow) return
thenCalledOrThrow = true
return reject(r)
})
} else {
return resolve(x)
}
} catch(e) {
if (thenCalledOrThrow) return
thenCalledOrThrow = true
return reject(e)
}
} else {
return resolve(x)
}
}
Promise.prototype.then = function(onResolved, onRejected) {
onResolved = typeof onResolved === 'function' ? onResolved : function(v){return v}
onRejected = typeof onRejected === 'function' ? onRejected : function(r){throw r}
var self = this
var promise2
if (self.status === 'resolved') {
return promise2 = new Promise(function(resolve, reject) {
setTimeout(function() {
try {
var x = onResolved(self.data)
resolvePromise(promise2, x, resolve, reject)
} catch(e) {
return reject(e)
}
})
})
}
if (self.status === 'rejected') {
return promise2 = new Promise(function(resolve, reject) {
setTimeout(function() {
try {
var x = onRejected(self.data)
resolvePromise(promise2, x, resolve, reject)
} catch(e) {
return reject(e)
}
})
})
}
if (self.status === 'pending') {
return promise2 = new Promise(function(resolve, reject) {
self.callbacks.push({
onResolved: function(value) {
try {
var x = onResolved(value)
resolvePromise(promise2, x, resolve, reject)
} catch(e) {
return reject(e)
}
},
onRejected: function(reason) {
try {
var x = onRejected(reason)
resolvePromise(promise2, x, resolve, reject)
} catch(e) {
return reject(e)
}
}
})
})
}
}
Promise.prototype.valueOf = function() {
return this.data
}
Promise.prototype.catch = function(onRejected) {
return this.then(null, onRejected)
}
Promise.prototype.finally = function(fn) {
// 为什么这里可以呢,因为所有的then调用是一起的,但是这个then里调用fn又异步了一次,所以它总是最后调用的。
// 当然这里只能保证在已添加的函数里是最后一次,不过这也是必然。
// 不过看起来比其它的实现要简单以及容易理解的多。
// 貌似对finally的行为没有一个公认的定义,所以这个实现目前是跟Q保持一致,会返回一个新的Promise而不是原来那个。
return this.then(function(v){
setTimeout(fn)
return v
}, function(r){
setTimeout(fn)
throw r
})
}
Promise.prototype.spread = function(fn, onRejected) {
return this.then(function(values) {
return fn.apply(null, values)
}, onRejected)
}
Promise.prototype.inject = function(fn, onRejected) {
return this.then(function(v) {
return fn.apply(null, fn.toString().match(/\((.*?)\)/)[1].split(',').map(function(key){
return v[key];
}))
}, onRejected)
}
Promise.prototype.delay = function(duration) {
return this.then(function(value) {
return new Promise(function(resolve, reject) {
setTimeout(function() {
resolve(value)
}, duration)
})
}, function(reason) {
return new Promise(function(resolve, reject) {
setTimeout(function() {
reject(reason)
}, duration)
})
})
}
Promise.all = function(promises) {
return new Promise(function(resolve, reject) {
var resolvedCounter = 0
var promiseNum = promises.length
var resolvedValues = new Array(promiseNum)
for (var i = 0; i < promiseNum; i++) {
(function(i) {
Promise.resolve(promises[i]).then(function(value) {
resolvedCounter++
resolvedValues[i] = value
if (resolvedCounter == promiseNum) {
return resolve(resolvedValues)
}
}, function(reason) {
return reject(reason)
})
})(i)
}
})
}
Promise.race = function(promises) {
return new Promise(function(resolve, reject) {
for (var i = 0; i < promises.length; i++) {
Promise.resolve(promises[i]).then(function(value) {
return resolve(value)
}, function(reason) {
return reject(reason)
})
}
})
}
Promise.resolve = function(value) {
var promise = new Promise(function(resolve, reject) {
resolvePromise(promise, value, resolve, reject)
})
return promise
}
Promise.reject = function(reason) {
return new Promise(function(resolve, reject) {
reject(reason)
})
}
Promise.fcall = function(fn){
// 虽然fn可以接收到上一层then里传来的参数,但是其实是undefined,所以跟没有是一样的,因为resolve没参数啊
return Promise.resolve().then(fn)
}
Promise.done = Promise.stop = function(){
return new Promise(function(){})
}
Promise.deferred = Promise.defer = function() {
var dfd = {}
dfd.promise = new Promise(function(resolve, reject) {
dfd.resolve = resolve
dfd.reject = reject
})
return dfd
}
try { // CommonJS compliance
module.exports = Promise
} catch(e) {}
return Promise
})()