From f46b338de7f90a8ab7ad0b63031a51fe4e74aae2 Mon Sep 17 00:00:00 2001
From: JSap0914 <JSap0914@users.noreply.github.com>
Date: Tue, 30 Jun 2026 12:38:09 +0900
Subject: [PATCH] fix(isRgbColor): accept alpha values with more than 2 decimal
 digits
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The alpha regex (0?\.\d\d?|1(\.0)?|0(\.0)?) limited alpha to at
most 2 decimal digits and did not allow trailing zeros on the boundary
values 1 and 0, causing valid CSS rgba() colors to be incorrectly
rejected:

  isRgbColor('rgba(255,255,255,.123)') // false — should be true
  isRgbColor('rgba(255,255,255,1.00)') // false — should be true
  isRgbColor('rgba(0,0,0,0.123)')      // false — should be true

The CSS specification defines <alpha-value> as a CSS <number>
(https://www.w3.org/TR/css-color-4/#typedef-alpha-value), which
imposes no limit on decimal precision.

Fix: widen the alpha sub-pattern to:
  (0?\.\d+|1(\.0+)?|0(\.0+)?)
so that any number of decimal digits after the point is accepted, and
both 1.0 and 1.00 (and similarly for 0) are valid.

Closes #2792
---
 src/lib/isRgbColor.js   | 4 ++--
 test/validators.test.js | 6 ++++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/lib/isRgbColor.js b/src/lib/isRgbColor.js
index a672df279..e9fb60253 100644
--- a/src/lib/isRgbColor.js
+++ b/src/lib/isRgbColor.js
@@ -2,9 +2,9 @@
 import assertString from './util/assertString';
 
 const rgbColor = /^rgb\((([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5]),){2}([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\)$/;
-const rgbaColor = /^rgba\((([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5]),){3}(0?\.\d\d?|1(\.0)?|0(\.0)?)\)$/;
+const rgbaColor = /^rgba\((([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5]),){3}(0?\.\d+|1(\.0+)?|0(\.0+)?)\)$/;
 const rgbColorPercent = /^rgb\((([0-9]%|[1-9][0-9]%|100%),){2}([0-9]%|[1-9][0-9]%|100%)\)$/;
-const rgbaColorPercent = /^rgba\((([0-9]%|[1-9][0-9]%|100%),){3}(0?\.\d\d?|1(\.0)?|0(\.0)?)\)$/;
+const rgbaColorPercent = /^rgba\((([0-9]%|[1-9][0-9]%|100%),){3}(0?\.\d+|1(\.0+)?|0(\.0+)?)\)$/;
 const startsWithRgb = /^rgba?/;
 
 export default function isRgbColor(str, options) {
diff --git a/test/validators.test.js b/test/validators.test.js
index 9c867efae..afd9a0998 100644
--- a/test/validators.test.js
+++ b/test/validators.test.js
@@ -5119,9 +5119,13 @@ describe('Validators', () => {
         'rgba(255,255,255,.1)',
         'rgba(255,255,255,0.1)',
         'rgba(255,255,255,.12)',
+        'rgba(255,255,255,.123)',
+        'rgba(255,255,255,1.00)',
+        'rgba(0,0,0,0.123)',
         'rgb(5%,5%,5%)',
         'rgba(5%,5%,5%,.3)',
         'rgba(5%,5%,5%,.32)',
+        'rgba(5%,5%,5%,.321)',
       ],
       invalid: [
         'rgb(0,0,0,)',
@@ -5130,12 +5134,10 @@ describe('Validators', () => {
         'rgb()',
         'rgba(0,0,0)',
         'rgba(255,255,255,2)',
-        'rgba(255,255,255,.123)',
         'rgba(255,255,256,0.1)',
         'rgb(4,4,5%)',
         'rgba(5%,5%,5%)',
         'rgba(3,3,3%,.3)',
-        'rgba(5%,5%,5%,.321)',
         'rgb(101%,101%,101%)',
         'rgba(3%,3%,101%,0.3)',
         'rgb(101%,101%,101%) additional invalid string part',