https://client.sharefull.com/js/firstInputDelay.js

1!(function (n, e) {
2  var t,
3    o,
4    i,
5    c = [],
6    f = { passive: !0, capture: !0 },
7    r = new Date(),
8    a = 'pointerup',
9    u = 'pointercancel'
10  function p(n, c) {
11    t || ((t = c), (o = n), (i = new Date()), w(e), s())
12  }
13  function s() {
14    o >= 0 &&
15      o < i - r &&
16      (c.forEach(function (n) {
17        n(o, t)
18      }),
19      (c = []))
20  }
21  function l(t) {
22    if (t.cancelable) {
23      var o =
24        (t.timeStamp > 1e12 ? new Date() : performance.now()) - t.timeStamp
25      'pointerdown' == t.type
26        ? (function (t, o) {
27            function i() {
28              ;(p(t, o), r())
29            }
30            function c() {
31              r()
32            }
33            function r() {
34              ;(e(a, i, f), e(u, c, f))
35            }
36            ;(n(a, i, f), n(u, c, f))
37          })(o, t)
38        : p(o, t)
39    }
40  }
41  function w(n) {
42    ;['click', 'mousedown', 'keydown', 'touchstart', 'pointerdown'].forEach(
43      function (e) {
44        n(e, l, f)
45      }
46    )
47  }
48  ;(w(n),
49    (self.perfMetrics = self.perfMetrics || {}),
50    (self.perfMetrics.onFirstInputDelay = function (n) {
51      ;(c.push(n), s())
52    }))
53})(addEventListener, removeEventListener)