docs: Show prerelease version in dropdown

docs/package.json

@@ -24,6 +24,7 @@
     },
     "devDependencies": {
         "@11ty/eleventy": "^2.0.1",
+        "@11ty/eleventy-fetch": "^4.0.0",
         "@11ty/eleventy-img": "^3.1.1",
         "@11ty/eleventy-navigation": "^0.3.5",
         "@11ty/eleventy-plugin-rss": "^1.1.1",

docs/src/_data/eslintNextVersion.js

@@ -0,0 +1,32 @@
+/**
+ * @fileoverview
+ * @author Nicholas C. Zakas
+ */
+
+//-----------------------------------------------------------------------------
+// Requirements
+//-----------------------------------------------------------------------------
+
+const eleventyFetch  = require("@11ty/eleventy-fetch");
+
+//-----------------------------------------------------------------------------
+// Exports
+//-----------------------------------------------------------------------------
+
+module.exports = async function() {
+
+    // if we're on the next branch, we can just read the package.json file
+    if (process.env.BRANCH === "next") {
+        return require("../../package.json").version;
+    }
+
+    // otherwise, we need to fetch the latest version from the GitHub API
+    const url = "https://raw.githubusercontent.com/eslint/eslint/next/docs/package.json";
+
+    const response = await eleventyFetch(url, {
+        duration: "1d",
+        type: "json"
+    });
+
+    return response.version;
+}

docs/src/_includes/components/nav-version-switcher.html

@@ -14,7 +14,7 @@
         <select name="version selector" id="nav-version-select" aria-describedby="nav-version-infobox" class="c-custom-select switcher__select auto-switcher">
             <option value="HEAD" data-url="/docs/head/" {% if HEAD %}selected{% endif %}>HEAD</option>
             {% if config.showNextVersion == true %}
-                <option value="NEXT" data-url="/docs/next/" {% if GIT_BRANCH == "next" %}selected{% endif %}>NEXT</option>
+                <option value="{{ eslintNextVersion }}" data-url="/docs/next/" {% if GIT_BRANCH == "next" %}selected{% endif %}>v{{ eslintNextVersion }}</option>
             {% endif %}
             <option value="{{ eslintVersion }}" data-url="/docs/latest/" {% if GIT_BRANCH == "latest" %}selected{% endif %}>v{{ eslintVersion }}</option>
             {% for version in versions.items %}

docs/src/_includes/components/version-switcher.html

@@ -14,7 +14,7 @@
         <select name="version selector" id="version-select" aria-describedby="version-infobox" class="c-custom-select switcher__select auto-switcher">
             <option value="HEAD" data-url="/docs/head/"  {% if HEAD %}selected{% endif %}>HEAD</option>
             {% if config.showNextVersion == true %}
-              <option value="NEXT" data-url="/docs/next/" {% if GIT_BRANCH=="next" %}selected{% endif %}>NEXT</option>
+              <option value="{{ eslintNextVersion }}" data-url="/docs/next/" {% if GIT_BRANCH=="next" %}selected{% endif %}>v{{ eslintNextVersion }}</option>
             {% endif %}
             <option value="{{ eslintVersion }}" data-url="/docs/latest/"  {% if GIT_BRANCH == "latest" %}selected{% endif %}>v{{ eslintVersion }}</option>
             {% for version in versions.items %}

docs/src/_includes/partials/versions-list.html

@@ -1,7 +1,7 @@
 <ul class="versions-list">
     <li><a href="/docs/head/" {% if HEAD %} data-current="true" {% endif %}>HEAD</a></li>
     {% if config.showNextVersion == true %}
-      <li><a href="/docs/next/" {% if GIT_BRANCH == "next" %} data-current="true" {% endif %}>NEXT</a></li>
+      <li><a href="/docs/next/" {% if GIT_BRANCH == "next" %} data-current="true" {% endif %}>v{{ eslintNextVersion }}</a></li>
     {% endif %}
     <li><a href="/docs/latest/" {% if GIT_BRANCH == "latest" %} data-current="true" {% endif %}>v{{ eslintVersion }}</a></li>
     {%- for version in versions.items -%}