Add spinner indicator

Author: yuanchuan

lib/handler.js

@@ -42,7 +42,9 @@ export async function handleRender(source, options) {
 
     try {
         const start = Date.now();
+        let spinner = showSpinner();
         const output = await render(content, options);
+        spinner.stop();
         const time = (Date.now() - start) / 1000;
         if (output) {
             console.log(`Saved to ${output}. (${time}s)`);
@@ -212,3 +214,18 @@ function readTime(number, options = {}) {
     }
     return Math.min(result, options.max ?? Infinity);
 }
+
+function showSpinner() {
+    let i = 0;
+    let spinner = ['|', '/', '-', '\\'];
+    let timer = setInterval(() => {
+        process.stdout.write(`\r${spinner[i++]}`);
+        i &= 3;
+    }, 100);
+    return {
+        stop: () => {
+            clearInterval(timer);
+            process.stdout.write('\r');
+        }
+    }
+}