feat(article): copy button for highlight block (#295)

This button only shows on highlighted code blocks, because it uses the wrapper div.highlight

assets/scss/partials/layout/article.scss

@@ -415,4 +415,30 @@
         margin-right: calc((var(--card-padding)) * -1);
         width: calc(100% + var(--card-padding) * 2);
     }
+
+    .highlight {
+        position: relative;
+
+        &:hover {
+            .copyCodeButton {
+                opacity: 1;
+            }
+        }
+    }
+
+    .copyCodeButton {
+        position: absolute;
+        top: calc(var(--card-padding));
+        right: 0;
+        background: var(--card-background);
+        border: none;
+        box-shadow: var(--shadow-l2);
+        border-radius: var(--tag-border-radius);
+        padding: 8px 16px;
+        color: var(--card-text-color-main);
+        cursor: pointer;
+        font-size: 14px;
+        opacity: 0;
+        transition: opacity 0.3s ease;
+    }
 }

assets/ts/main.ts

@@ -54,6 +54,38 @@ let Stack = {
             observer.observe(articleTile)
         }
 
+
+        /**
+         * Add copy button to code block
+        */
+        const codeBlocks = document.querySelectorAll('.article-content .highlight');
+        const copyText = `Copy`,
+            copiedText = `Copied!`;
+        codeBlocks.forEach(codeBlock => {
+            const copyButton = document.createElement('button');
+            copyButton.innerHTML = copyText;
+            copyButton.classList.add('copyCodeButton');
+            codeBlock.appendChild(copyButton);
+
+            const pre = codeBlock.getElementsByTagName('pre');
+            const code = pre[0].textContent;
+
+            copyButton.addEventListener('click', () => {
+                navigator.clipboard.writeText(code)
+                    .then(() => {
+                        copyButton.textContent = copiedText;
+
+                        setTimeout(() => {
+                            copyButton.textContent = copyText;
+                        }, 1000);
+                    })
+                    .catch(err => {
+                        alert(err)
+                        console.log('Something went wrong', err);
+                    });
+            });
+        });
+
         new StackColorScheme(document.getElementById('dark-mode-toggle'));
     }
 }