hex string normalisation and get value from field

apps/static/js/home/index.js

@@ -86,11 +86,30 @@ $(".colour-control-text").on("change", function() {
 });
 
 function updateColourInput(id, hexString) {
-    hexString = hexString.toUpperCase();
+    hexString = normaliseHexString(hexString.toUpperCase());
     $(`#${id} .colour-picker`).val(hexString);
     $(`#${id} .colour-text`).val(hexString);
 }
 
+function getColourInputVal(id, includeHashtag=true) {
+    const hexString = $(`#${id}Text`).val();
+    return normaliseHexString(hexString, includeHashtag);
+}
+
+function normaliseHexString(hexString, includeHashtag=true) {
+    console.debug(`normalising hex string '${hexString}' include hashtag '${includeHashtag}'`);
+
+    // Remove any non-hex characters (e.g., additional hashtags)
+    hexString = hexString.replace(/[^A-F0-9]/gi, '');
+
+    // Ensure the hex string has a valid length of either 3, 6, or 8 characters
+    if (![3, 6, 8].includes(hexString.length)) {
+        throw new Error(`Invalid hex string length. Must be 3, 6, or 8 characters. hexString=${hexString}`);
+    }
+
+    return includeHashtag ? `#${hexString}` : hexString;
+}
+
 $(document).ready(function() {
     $(".colour-input").each(function() {
         let id = $(this).attr("data-id")