feat: sanitize HTML in footer

moved sanitize function into a separate file including some simple tests

closes #91

src/sanitize.test.tsx

@@ -0,0 +1,20 @@
+import { sanitize } from "./sanitize";
+
+describe("sanitize", () => {
+  it("should sanitize the string input to HTML output", () => {
+    let res = sanitize('foo');
+    expect(res.__html).toEqual("foo");
+    res = sanitize('<a href="https://example.org">Example.org</a>');
+    expect(res.__html).toEqual("<a href=\"https://example.org\">Example.org</a>");
+  });
+  it("should not sanitize not allowed tags", () => {
+    let res = sanitize('Before <iframe src="https://example.org"></iframe> After');
+    expect(res.__html).toEqual("Before  After");
+  });
+  it("should accept options for rendering", () => {
+    let res = sanitize('<a href="https://example.org" target="_blank">Example.org</a>', { allowedAttributes: { a: ['href']}});
+    expect(res.__html).toEqual("<a href=\"https://example.org\">Example.org</a>");
+  });
+});
+
+