hide search buttons if search not supported

site/_static/scripts/browser-support.js

@@ -0,0 +1,102 @@
+function test_webp_feature(feature, callback) {
+    // Test webp feature.
+    //   'feature' can be one of 'lossy', 'lossless', 'alpha' or 'animation'.
+    //   'callback(feature, isSupported)' will be passed back the detection result (in an asynchronous way!).
+    //    Copied from https://developers.google.com/speed/webp/faq#in_your_own_javascript
+    var kTestImages = {
+            lossy: "UklGRiIAAABXRUJQVlA4IBYAAAAwAQCdASoBAAEADsD+JaQAA3AAAAAA",
+            lossless: "UklGRhoAAABXRUJQVlA4TA0AAAAvAAAAEAcQERGIiP4HAA==",
+            alpha: "UklGRkoAAABXRUJQVlA4WAoAAAAQAAAAAAAAAAAAQUxQSAwAAAARBxAR/Q9ERP8DAABWUDggGAAAABQBAJ0BKgEAAQAAAP4AAA3AAP7mtQAAAA==",
+            animation: "UklGRlIAAABXRUJQVlA4WAoAAAASAAAAAAAAAAAAQU5JTQYAAAD/////AABBTk1GJgAAAAAAAAAAAAAAAAAAAGQAAABWUDhMDQAAAC8AAAAQBxAREYiI/gcA"
+        };
+        var img = new Image();
+        img.onload = function () {
+            var result = (img.width > 0) && (img.height > 0);
+            callback(feature, result);
+        };
+        img.onerror = function () {
+            callback(feature, false);
+        };
+        img.src = "data:image/webp;base64," + kTestImages[feature];
+}
+
+function create_announcement(innerHtml) {
+    // Return an announcement element.
+    // Format was reverse-engineered from pydata-sphinx-theme v0.13.3 generated index.html with 
+    // html_theme_options["announcement"] set in conf.py.
+
+    if (!innerHtml) innerHtml = "<b>This site requires webp support to display images.  Please update your browser.</b>";
+
+    var ann = document.createElement("div");
+    ann.classList.add("bd-header-announcement");
+    ann.innerHTML = innerHtml;
+
+    return ann;
+}
+
+var webpSupport = null;
+
+function test_webp_support() {
+    // General test for webp support over features.  Adds an announcement if any feature not 
+    // supported.
+    webpSupport = true;
+
+    var webp_callback = function (feature, isSupported) {
+
+        if (!isSupported && webpSupport != false) {
+            webpSupport = false;
+            document.body.insertBefore(create_announcement(), document.body.firstChild);
+        }
+    }
+    var features = ["lossy", "lossless", "alpha"];
+    features.forEach(function (feature, index) {
+        test_webp_feature(feature, webp_callback);
+    });
+}
+
+
+function test_search_support() {
+    // Disable search button(s) if search not supported.  
+    // Support is tested with a basic check for existence of searchtools.js, doctools.js & 
+    //  sphinx_highlight.js modules.
+    try {
+        // try create Search and dependent modules
+        var checkList = [Search, Documentation, SphinxHighlight, _ready]; 
+
+        // var msg = "<b>Search ok.</b>";
+        // var searchElems = document.getElementsByClassName("search-button");
+        // for (var i = 0; i < searchElems.length; i++) {
+        //     searchElems[i].style.backgroundColor = "green";
+        // }
+        // document.body.insertBefore(create_announcement(msg), document.body.firstChild);
+    } 
+    catch (ex) {
+        // hide search buttons
+        var searchElems = document.getElementsByClassName("search-button");
+        for (var i = 0; i < searchElems.length; i++) {
+            // searchElems[i].style.backgroundColor = "red";
+            searchElems[i].style.display = "none";
+        }
+
+        // msg = "<b>Search not ok.</b>";
+        // document.body.insertBefore(create_announcement(msg), document.body.firstChild);
+        console.log("Search not supported: " + String(ex));
+        // throw(ex);
+    }
+}
+
+// Override splitQuery in searchtools.js which specifies a unicode regex not supported by all
+// browsers
+// var splitQuery = function(query) {
+//     // change "/[^\p{Letter}\p{Number}_\p{Emoji_Presentation}]+/gu" to ascii only expression 
+//     return query.split(/[^A-Za-z0-9_]+/g).filter(function(term) { return term; });
+// }
+
+if (document.readyState !== "loading") {
+    test_webp_support();
+    test_search_support();    
+} else {
+    document.addEventListener("DOMContentLoaded", test_webp_support);
+    document.addEventListener("DOMContentLoaded", test_search_support);
+}
+

site/conf.py

@@ -38,7 +38,9 @@
 html_static_path = ['_static']
 # colour styles must come before no-flex
 html_css_files = ['styles/leftfield.css']
-html_js_files = ['scripts/webp-support.js']
+# searchtools.js is a theme script that is always incuded, but is specified here to make sure it is 
+# listed in the html before browser-support.js, which uses it. 
+html_js_files = ['searchtools.js', 'scripts/browser-support.js']
 html_context = {'default_mode': 'auto'}  # use the system/browser light/dark theme setting
 # html_favicon = '_static/favicons/favicon.svg'
 html_sourcelink_suffix = ''