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
'use strict';
module.exports = parallelLimit;
/*! * ignore */
function parallelLimit(fns, limit, callback) {  let numInProgress = 0;  let numFinished = 0;  let error = null;
  if (limit <= 0) {    throw new Error('Limit must be positive');  }
  if (fns.length === 0) {    return callback(null, []);  }
  for (let i = 0; i < fns.length && i < limit; ++i) {    _start();  }
  function _start() {    fns[numFinished + numInProgress](_done(numFinished + numInProgress));    ++numInProgress;  }
  const results = [];
  function _done(index) {    return (err, res) => {      --numInProgress;      ++numFinished;
      if (error != null) {        return;      }      if (err != null) {        error = err;        return callback(error);      }
      results[index] = res;
      if (numFinished === fns.length) {        return callback(null, results);      } else if (numFinished + numInProgress < fns.length) {        _start();      }    };  }}