toggle-lang.html

<script>
    function toggleLang() {
        var origin = window.location.origin;
        var pathname = window.location.pathname;
        var search = window.location.search;
        var hash = window.location.hash;

        // This is your site's base path (without trailing slash)
        var basePath = "/GEMS-MagTIP";

        // Check if currently in Chinese version by looking for "/zh-TW/" segment
        if (pathname.indexOf(basePath + "/zh-TW/") === 0 || pathname === basePath + "/zh-TW") {
            // We are in the Chinese site, so remove 'zh-TW' to go back to English
            var newPath = pathname.replace("/zh-TW", "");
            window.location.href = origin + newPath + search + hash;
        } else {
            // We are in the English site, so insert '/zh-TW' after base path
            // Make sure we only insert if not already present
            if (pathname.indexOf(basePath) === 0) {
                var newPath = pathname.replace(basePath, basePath + "/zh-TW");
                window.location.href = origin + newPath + search + hash;
            } else {
                // If for some reason the current path doesn't start with the known base, 
                // fallback to just adding zh-TW after origin.
                window.location.href = origin + basePath + "/zh-TW" + pathname + search + hash;
            }
        }
    }


</script>

<!-- This is a javascript to be included every page. See  include-after-body: ... in .qmd headers.-->
<!-- 
Prompt:
I have a website. The english site is under `<baseurl>/`, where as the Chinese version is under `<baseurl>/zh-TW/`. Please help me write a javascript function `toggleLang` which can help me switch between these two versions. For example, when I'm at `<baseurl>/whatever/page`, call the function via `javascript:toggleLang();` will jump to `<baseurl>/zh-TW/whatever/page`; on the other hand, when I'm at `<baseurl>/zh-TW/whatever/page`, call the function jumps to `<baseurl>/whatever/page`.

KEYNOTE:
- ChatGPT doesn't do this job well. `basePath` is critical to make this script works.
 -->