year check valid or not All form commit

static/js/year_dropdown.js

@@ -1,23 +1,51 @@
 document.addEventListener("DOMContentLoaded", function () {
   const yearDropdown = document.getElementById("year");
+  const errorDiv = document.getElementById("yearError");
+
+  // Get the form dynamically
+  const form = document.querySelector("form"); // get from id as table name
+
+  // Dynamic table name = form id
+  const tableName = form.id.toLowerCase();
 
   const currentYear = new Date().getFullYear();
   const startYear = 1990;
 
+  // Fill Year dropdown
   for (let y = currentYear; y >= startYear; y--) {
     let nextYear = y + 1;
 
     let option = document.createElement("option");
-
-    // Backend receives only first year (example 2024)
     option.value = y;
-
-    // User sees (example AY 2024–2025)
     option.textContent = `AY ${y}-${nextYear}`;
 
     yearDropdown.appendChild(option);
   }
+
+  // Validate selected year
+  yearDropdown.addEventListener("change", function () {
+    let selectedYear = parseInt(this.value);
+
+    fetch("/check_year", {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({
+        table: tableName,  // dynamic table name
+        year: selectedYear
+      })
+    })
+      .then(res => res.json())
+      .then(data => {
+        if (data.exists) {
+          errorDiv.style.display = "block";
+          errorDiv.innerText = `Year ${selectedYear} already exists!`;
+
+          // Block submission
+          form.onsubmit = function () { return false; };
+        } else {
+          errorDiv.style.display = "none";
+          form.onsubmit = null; // Allow submit
+        }
+      });
+  });
 });
-
-
-