aaac7fed
 liuqimichale
add
|
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
|
'use strict';
// there's 3 implementations written in increasing order of efficiency
// 1 - no Set type is defined
function uniqNoSet(arr) {
var ret = [];
for (var i = 0; i < arr.length; i++) {
if (ret.indexOf(arr[i]) === -1) {
ret.push(arr[i]);
}
}
return ret;
}
// 2 - a simple Set type is defined
function uniqSet(arr) {
var seen = new Set();
return arr.filter(function (el) {
if (!seen.has(el)) {
seen.add(el);
return true;
}
return false;
});
}
// 3 - a standard Set type is defined and it has a forEach method
function uniqSetWithForEach(arr) {
var ret = [];
(new Set(arr)).forEach(function (el) {
ret.push(el);
});
return ret;
}
// V8 currently has a broken implementation
// https://github.com/joyent/node/issues/8449
function doesForEachActuallyWork() {
var ret = false;
(new Set([true])).forEach(function (el) {
ret = el;
});
return ret === true;
}
if ('Set' in global) {
if (typeof Set.prototype.forEach === 'function' && doesForEachActuallyWork()) {
module.exports = uniqSetWithForEach;
} else {
module.exports = uniqSet;
}
} else {
module.exports = uniqNoSet;
}
|
