number_to_hex.js

var text = document.getElementById('text');
for (var i = 1; i >= 0; i -= 0.01) {
  i = Math.round(i * 100) / 100;
  var alpha = Math.round(i * 255);
  var hex = (alpha + 0x10000).toString(16).substr(-2).toUpperCase();
  var perc = Math.round(i * 100);
  text.innerHTML += perc + "% — " + hex + " (" + alpha + ")</br>";
}
<div id="text"></div>

result.txt

100% — FF (255)
99% — FC (252)
98% — FA (250)
97% — F7 (247)
96% — F5 (245)
95% — F2 (242)
94% — F0 (240)
93% — ED (237)
92% — EB (235)
91% — E8 (232)
90% — E6 (230)
89% — E3 (227)
88% — E0 (224)
87% — DE (222)
86% — DB (219)
85% — D9 (217)
84% — D6 (214)
83% — D4 (212)
82% — D1 (209)
81% — CF (207)
80% — CC (204)
79% — C9 (201)
78% — C7 (199)
77% — C4 (196)
76% — C2 (194)
75% — BF (191)
74% — BD (189)
73% — BA (186)
72% — B8 (184)
71% — B5 (181)
70% — B3 (179)
69% — B0 (176)
68% — AD (173)
67% — AB (171)
66% — A8 (168)
65% — A6 (166)
64% — A3 (163)
63% — A1 (161)
62% — 9E (158)
61% — 9C (156)
60% — 99 (153)
59% — 96 (150)
58% — 94 (148)
57% — 91 (145)
56% — 8F (143)
55% — 8C (140)
54% — 8A (138)
53% — 87 (135)
52% — 85 (133)
51% — 82 (130)
50% — 80 (128)
49% — 7D (125)
48% — 7A (122)
47% — 78 (120)
46% — 75 (117)
45% — 73 (115)
44% — 70 (112)
43% — 6E (110)
42% — 6B (107)
41% — 69 (105)
40% — 66 (102)
39% — 63 (99)
38% — 61 (97)
37% — 5E (94)
36% — 5C (92)
35% — 59 (89)
34% — 57 (87)
33% — 54 (84)
32% — 52 (82)
31% — 4F (79)
30% — 4D (77)
29% — 4A (74)
28% — 47 (71)
27% — 45 (69)
26% — 42 (66)
25% — 40 (64)
24% — 3D (61)
23% — 3B (59)
22% — 38 (56)
21% — 36 (54)
20% — 33 (51)
19% — 30 (48)
18% — 2E (46)
17% — 2B (43)
16% — 29 (41)
15% — 26 (38)
14% — 24 (36)
13% — 21 (33)
12% — 1F (31)
11% — 1C (28)
10% — 1A (26)
9% — 17 (23)
8% — 14 (20)
7% — 12 (18)
6% — 0F (15)
5% — 0D (13)
4% — 0A (10)
3% — 08 (8)
2% — 05 (5)
1% — 03 (3)
0% — 00 (0)