Get scheme cookie server-side instead of client-side on page load

public/js/schemeSwap.js

@@ -0,0 +1,53 @@
+/**
+ * Retrieves a cookies value
+ * @param {string} cname Cookie name
+ * @returns {string}     Cookie value
+ */
+function getCookie(cname) {
+    let name = cname + "=";
+    let decodedCookie = decodeURIComponent(document.cookie);
+    let ca = decodedCookie.split(';');
+    for(let i = 0; i <ca.length; i++) {
+        let c = ca[i];
+        while (c.charAt(0) == ' ') {
+            c = c.substring(1);
+        }
+        if (c.indexOf(name) == 0) {
+            return c.substring(name.length, c.length);
+        }
+    }
+    return "";
+}
+
+/**
+ * Sets/creates a cookie
+ * @param {string} cname  Cookie name
+ * @param {string} cvalue Cookie value
+ * @param {number} exdays Cookie lifespan (days)
+ */
+function setCookie(cname, cvalue, exdays) {
+    const d = new Date();
+    d.setTime(d.getTime() + (exdays*24*60*60*1000));
+    let expires = "expires="+ d.toUTCString();
+    document.cookie = cname + "=" + cvalue + ";" + expires + ";path=/";
+}
+
+/**
+ * Checks if a cookie exists
+ * @param {string} cname Cookie name
+ * @returns {boolean}    If cookie exists or not
+ */
+function cookieExists(cname) {
+    const cvalue = getCookie(cname);
+    return cvalue !== "";
+}
+
+/**
+ * Swaps the colorscheme
+ * @param {string} scheme Color scheme ID
+ */
+function swapScheme(scheme) {
+    setCookie("colorscheme", scheme, 90);
+    document.getElementById("css-colorscheme").href = `/css/colorschemes/${scheme}.css`;
+    console.log(`Set colorscheme to ${getCookie("colorscheme")}`)
+}