tools: add button to copy code example to clipboard

PR-URL: https://github.com/nodejs/node/pull/46928
Refs: https://github.com/nodejs/node/issues/46894
Reviewed-By: Debadree Chatterjee <debadree333@gmail.com>

doc/api_assets/api.js

@@ -136,6 +136,36 @@
     updateHashes();
   }
 
+  function setupCopyButton() {
+    const buttons = document.querySelectorAll('.copy-button');
+    buttons.forEach((button) => {
+      button.addEventListener('click', (el) => {
+        const parentNode = el.target.parentNode;
+
+        const flavorSelector = parentNode.querySelector('.js-flavor-selector');
+
+        let code = '';
+
+        if (flavorSelector) {
+          if (flavorSelector.checked) {
+            code = parentNode.querySelector('.mjs').textContent;
+          } else {
+            code = parentNode.querySelector('.cjs').textContent;
+          }
+        } else {
+          code = parentNode.querySelector('code').textContent;
+        }
+
+        button.textContent = 'Copied';
+        navigator.clipboard.writeText(code);
+
+        setTimeout(() => {
+          button.textContent = 'Copy';
+        }, 2500);
+      });
+    });
+  }
+
   function bootstrap() {
     // Check if we have JavaScript support.
     document.documentElement.classList.add('has-js');
@@ -151,6 +181,8 @@
 
     // Make link to other versions of the doc open to the same hash target (if it exists).
     setupAltDocsLink();
+
+    setupCopyButton();
   }
 
   if (document.readyState === 'loading') {

doc/api_assets/style.css

@@ -973,6 +973,33 @@ kbd {
 .dark-mode .js-flavor-selector {
   filter: invert(1);
 }
+
+.copy-button {
+  float: right;
+  
+  outline: none;
+  font-size: 10px;
+  color: #fff;
+  background-color: var(--green1);
+  line-height: 1;
+  border-radius: 500px;
+  border: 1px solid transparent;
+  letter-spacing: 2px;
+  min-width: 7.5rem;
+  text-transform: uppercase;
+  font-weight: 700;
+  padding: 0 .5rem;
+  margin-right: .2rem;
+  height: 1.5rem;
+  transition-property: background-color,border-color,color,box-shadow,filter;
+  transition-duration: .3s;
+  cursor: pointer;
+}
+
+.copy-button:hover {
+  background-color: var(--green2);
+}
+
 @supports (aspect-ratio: 1 / 1) {
   .js-flavor-selector {
     height: 1.5em;

tools/doc/html.mjs

@@ -226,10 +226,13 @@ export function preprocessElements({ filename }) {
         const className = isJSFlavorSnippet(node) ?
           `language-js ${node.lang}` :
           `language-${node.lang}`;
+
         const highlighted =
           `<code class='${className}'>${(getLanguage(node.lang || '') ? highlight(node.value, { language: node.lang }) : node).value}</code>`;
         node.type = 'html';
 
+        const copyButton = '<button class="copy-button">copy</button>';
+
         if (isJSFlavorSnippet(node)) {
           const previousNode = parent.children[index - 1] || {};
           const nextNode = parent.children[index + 1] || {};
@@ -253,16 +256,17 @@ export function preprocessElements({ filename }) {
               ' aria-label="Show modern ES modules syntax">' +
               previousNode.value +
               highlighted +
+              copyButton +
               '</pre>';
             node.lang = null;
             previousNode.value = '';
             previousNode.lang = null;
           } else {
             // Isolated JS snippet, no need to add the checkbox.
-            node.value = `<pre>${highlighted}</pre>`;
+            node.value = `<pre>${highlighted} ${copyButton}</pre>`;
           }
         } else {
-          node.value = `<pre>${highlighted}</pre>`;
+          node.value = `<pre>${highlighted} ${copyButton}</pre>`;
         }
       } else if (node.type === 'html' && common.isYAMLBlock(node.value)) {
         node.value = parseYAML(node.value);