add tab support for textareas

assets/js/app.js

@@ -64,3 +64,22 @@ document
             window.localStorage.setItem("theme", "dark")
         }
     })
+
+document
+    .querySelectorAll('textarea')
+    .forEach(e => e.addEventListener('keydown', function(e) {
+      if (e.key == 'Tab') {
+        e.preventDefault();
+        var start = this.selectionStart;
+        var end = this.selectionEnd;
+
+        // set textarea value to: text before caret + tab + text after caret
+        this.value = this.value.substring(0, start) +
+          "\t" + this.value.substring(end);
+
+        // put caret at right position again
+        this.selectionStart =
+          this.selectionEnd = start + 1;
+      }
+    }))
+