do not attempt to clear canvas if one does not exist

chartjs · May 7, 2024 · 02d4151 · 02d4151
1 parent 334fdf7
commit 02d4151
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Showing 2 changed files with 14 additions and 1 deletion.
diff --git a/src/helpers/helpers.canvas.ts b/src/helpers/helpers.canvas.ts
@@ -131,7 +131,11 @@ export function _alignPixel(chart: Chart, pixel: number, width: number) {
 /**
  * Clears the entire canvas.
  */
-export function clearCanvas(canvas: HTMLCanvasElement, ctx?: CanvasRenderingContext2D) {
+export function clearCanvas(canvas?: HTMLCanvasElement, ctx?: CanvasRenderingContext2D) {
+  if (!ctx && !canvas) {
+    return;
+  }
+
   ctx = ctx || canvas.getContext('2d');
 
   ctx.save();

diff --git a/test/specs/helpers.canvas.tests.js b/test/specs/helpers.canvas.tests.js
@@ -21,6 +21,15 @@ describe('Chart.helpers.canvas', function() {
       expect(chart.ctx.clearRect.calls.first().object).toBe(chart.ctx);
       expect(chart.ctx.clearRect.calls.first().args).toEqual([0, 0, 150, 245]);
     });
+
+    it('should not throw error when chart is null', function() {
+      function createChart() {
+        return acquireChart({}, {
+          canvas: null
+        })}
+
+      expect(createChart).not.toThrow();
+    });
   });
 
   describe('isPointInArea', function() {