Adds internal and external links

src/utils/url-paths.ts

@@ -1,12 +1,26 @@
 import urljoin from "url-join";
 
+/**
+ * Matches:
+ * - ftp://
+ * - https://
+ * - //
+ */
+export const absolutePathRegex = /^(?:[a-z]+:)?\/\//;
+
 export const isRelativePath = (str: string) => {
-    return str.startsWith('./') || /^\w/.exec(str);
+    const isAbsolute = absolutePathRegex.exec(str);
+    if (isAbsolute) return false;
+    // Matches simple `test.png` links
+    const simpleRelativePath = /^\w/.exec(str);
+    return str.startsWith('./') || str.startsWith('/') || (
+        simpleRelativePath
+    )
 }
 
 export const getFullRelativePath = (slug: string, srcStr: string) => {
     if (srcStr.startsWith('./')) srcStr = srcStr.slice(2);
-    return isRelativePath(srcStr) ?
+    return isRelativePath(srcStr) && !srcStr.startsWith('/') ?
         // URLJoin doesn't seem to handle the `./` well
         urljoin('/posts', slug, srcStr)
         : srcStr