More robust relative path handling

1 files changed, 12 insertions, 0 deletions

diff --git a/src/lib/relativePath.ts b/src/lib/relativePath.ts
new file mode 100644
index 0000000..ad8582c
--- /dev/null
+++ b/src/lib/relativePath.ts
@@ -0,0 +1,12 @@
+export default function (currentPath: string, relativePath: string) {
+  if (relativePath.length > 2 && relativePath.slice(0, 3) === '../') {
+    throw new Error('Cannot calculate relative path because it goes up a directory.');
+  }
+
+  if (currentPath.at(-1) !== '/') {
+    currentPath = currentPath + '/';
+  }
+  relativePath = relativePath.replace(/^\.?\//, '');
+
+  return currentPath + relativePath;
+}