37 lines
929 B
Plaintext
37 lines
929 B
Plaintext
/**
|
|
* Copyright (c) 2013-present, Facebook, Inc.
|
|
* All rights reserved.
|
|
*
|
|
* This source code is licensed under the BSD-style license found in the
|
|
* LICENSE file in the root directory of this source tree. An additional grant
|
|
* of patent rights can be found in the PATENTS file in the same directory.
|
|
*
|
|
* @providesModule minBy
|
|
* @flow
|
|
*/
|
|
|
|
var compareNumber = (a, b) => a - b;
|
|
|
|
/**
|
|
* Returns the minimum element as measured by a scoring function f. Returns the
|
|
* first such element if there are ties.
|
|
*/
|
|
function minBy<A, B>(as: Iterable<A>, f: (a: A) => B, compare?: ?(u: B, v: B) => number): ?A {
|
|
compare = compare || (compareNumber: any);
|
|
|
|
var minA = undefined;
|
|
var minB = undefined;
|
|
var seenFirst = false;
|
|
for (var a of as) {
|
|
var b = f(a);
|
|
if (!seenFirst || compare(b, (minB: any)) < 0) {
|
|
minA = a;
|
|
minB = b;
|
|
seenFirst = true;
|
|
}
|
|
}
|
|
|
|
return minA;
|
|
}
|
|
|
|
module.exports = minBy; |