-
Notifications
You must be signed in to change notification settings - Fork 0
/
pinkyPromise.js
49 lines (41 loc) · 1.12 KB
/
pinkyPromise.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
'use strict';
function pinkyPromise(fn) {
var queue = [];
function promisify(fn) {
// converts fn w/ callback to return promise
return function() {
var promise = pinkyPromise();
var args = Array.prototype.slice.call(arguments);
// add promise.resolve as final argument
args.push(promise.resolve);
fn.apply(this, args);
return promise;
};
}
function resolve(ret) {
if (!queue.length) {
// no more callbacks
return;
} else if (ret && ret.then) {
// ret is a promise
ret.then(resolve);
} else {
// ret is not a promise
var newRet = queue.shift()(ret);
resolve(newRet);
}
}
// if fn, return promisified fn
// otherwise return a promise
return fn ? promisify(fn) : {
then: function(cb) {
if (cb) {
// add cb to queue
queue.push(cb);
}
return this;
},
resolve: resolve
};
}
module.exports = pinkyPromise;