Add assets.

assets/js/mastodon-share.js

@@ -0,0 +1,68 @@
+
+// I got the key, I got the secret…
+let key = 'mastodon-instance';
+let instance = localStorage.getItem(key);
+
+// get the link from the DOM
+const button = document.querySelector('.mastodon-share');
+
+// refresh the link with the instance name
+const refreshlink = (instance) => {
+    button.href = `https://${instance}/share?text=${encodeURIComponent(document.title)}%0A${encodeURIComponent(location.href)}`;
+}
+
+// got it? Let's go! 
+if (button) {
+    // labels and texts from the link
+    let prompt = button.dataset.prompt || 'Please tell me your Mastodon instance';
+    let editlabel = button.dataset.editlabel || 'Edit your Mastodon instance';
+    let edittext = button.dataset.edittext || '✏️';
+
+    // Ask the user for the instance name and set it…
+    const setinstance = _ => {
+        instance = window.prompt(prompt, instance);
+        if(instance) {
+            localStorage.setItem(key, instance);
+            createeditbutton();
+            refreshlink(instance);
+            button.click();
+        }
+    }
+    
+    // create and insert the edit link
+    const createeditbutton = _ => {
+        if (document.querySelector('button.mastodon-edit')) return;
+        let editlink = document.createElement('button');
+          editlink.innerText = edittext;
+          editlink.classList.add('mastodon-edit');
+          editlink.title = editlabel;
+          editlink.ariaLabel = editlabel;
+          editlink.addEventListener('click', (e) => {
+              e.preventDefault();
+              localStorage.removeItem(key);
+              setinstance();
+          });
+          button.insertAdjacentElement('afterend', editlink);
+    }
+    
+    // if there is  a value in localstorage, create the edit link
+    if(localStorage.getItem(key)) {
+        createeditbutton();
+    }  
+    
+    // When a user clicks the link
+    button.addEventListener('click', (e) => {
+
+        // If the user has already entered their instance 
+        // and it is in localstorage write out the link href 
+        // with the instance and the current page title and URL
+        if(localStorage.getItem(key)) {
+            refreshlink(localStorage.getItem(key));
+            // otherwise, prompt the user for their instance and save it to localstorage
+        } else {
+            e.preventDefault();
+            setinstance();
+        }
+
+    });
+}