docs: use dropdown menu for selecting version (#6559)

Author: gsquared94

docs/layouts/partials/page-meta-links.html

@@ -9,9 +9,8 @@
 {{ if in .Permalink "/docs/references/yaml"}}
     <br>
     <div>Schema Versions</div>
-    <div id="schema_links">
-
-    </div>
+    <select id="schema_links" onchange="selectSchema(this)">
+    </select>
     <ul id="schema_list" hidden>
     {{ range (readDir "/content/en/schemas") }}
         <li>{{ trim .Name ".json" }}</li>

docs/static/javascripts/schemas.js

@@ -1,5 +1,7 @@
 const schema_list = [...document.getElementById("schema_list").getElementsByTagName("li")].map(l => l.textContent);
+const selectElement = document.getElementById("schema_links")
 const majors = {};
+const version = getCurrentSchemaVersion()
 for (let s of schema_list) {
     let i = 2;
     for (; i < s.length; i++) {
@@ -20,11 +22,28 @@ for (let s of schema_list) {
 }
 
 Object.keys(majors)
-    .sort()
+    .sort().reverse()
     .forEach(function(major) {
-        majors[major].sort((a,b) => a-b);
+        majors[major].sort((a,b) => b-a);
         for (const minor of majors[major]) {
-            const version = major + minor;
-            $("#schema_links").last().after($(`<a href="/docs/references/yaml/?version=${version}">${version}</a>`));
+            const v = major + minor;
+            selectElement.append(new Option(v, v, v === version, v === version));
         }
     });
+
+function selectSchema(selectObject) {
+    var value = selectObject.value;
+    if (value != "") {
+        location.href = `/docs/references/yaml/?version=${value}`
+    }
+}
+
+function getCurrentSchemaVersion() {
+    const versionParam = "?version=";
+    const index = window.location.href.indexOf(versionParam);
+    if (index === -1) {
+        return "";
+    } else {
+        return window.location.href.substr(index + versionParam.length);
+    }
+}