From 525a7de8ae7983a6d0e3b8cc299d524147d25abb Mon Sep 17 00:00:00 2001
From: darshanr0107 <darshan@mermaidchart.com>
Date: Mon, 15 Sep 2025 12:12:47 +0530
Subject: [PATCH] fix:gant chart crashing in browser

on-behalf-of: @Mermaid-Chart <hello@mermaidchart.com>
---
 cypress/integration/rendering/gantt.spec.js   | 30 +++++++++++++++++++
 .../mermaid/src/diagrams/gantt/ganttDb.js     |  4 ++-
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/cypress/integration/rendering/gantt.spec.js b/cypress/integration/rendering/gantt.spec.js
index 32dbcb4d9..72cb6ea29 100644
--- a/cypress/integration/rendering/gantt.spec.js
+++ b/cypress/integration/rendering/gantt.spec.js
@@ -803,4 +803,34 @@ describe('Gantt diagram', () => {
       {}
     );
   });
+  it('should handle numeric timestamps with dateFormat x', () => {
+    imgSnapshotTest(
+      `
+     gantt
+     title Process time profile (ms)
+     dateFormat x
+     axisFormat %L
+     tickInterval 250millisecond
+
+     section Pipeline
+     Parse JSON p1: 000, 120
+    `,
+      {}
+    );
+  });
+  it('should handle numeric timestamps with dateFormat X', () => {
+    imgSnapshotTest(
+      `
+     gantt
+     title Process time profile (ms)
+     dateFormat X
+     axisFormat %L
+     tickInterval 250millisecond
+
+     section Pipeline
+     Parse JSON p1: 000, 120
+    `,
+      {}
+    );
+  });
 });
diff --git a/packages/mermaid/src/diagrams/gantt/ganttDb.js b/packages/mermaid/src/diagrams/gantt/ganttDb.js
index b2b5b0566..b1b2052c1 100644
--- a/packages/mermaid/src/diagrams/gantt/ganttDb.js
+++ b/packages/mermaid/src/diagrams/gantt/ganttDb.js
@@ -268,7 +268,9 @@ const fixTaskDates = function (startTime, endTime, dateFormat, excludes, include
 
 const getStartDate = function (prevTime, dateFormat, str) {
   str = str.trim();
-
+  if ((dateFormat.trim() === 'x' || dateFormat.trim() === 'X') && /^\d+$/.test(str)) {
+    return new Date(Number(str));
+  }
   // Test for after
   const afterRePattern = /^after\s+(?<ids>[\d\w- ]+)/;
   const afterStatement = afterRePattern.exec(str);