Calculates delta from last time rather than zero

index.html

@@ -3,6 +3,7 @@
     <title>Test</title>
     <script type="text/javascript">
       const originalTime = new Date().getTime();
+      let lastTime = originalTime;
       const main = () => {
         let requestCount = 0;
         const outputElement = document.getElementById("output");
@@ -14,15 +15,17 @@
           if (response.ok) {
             requestCount++;
             const responseJson = await response.json();
-            const outputLine = `Response success [${response.status}] n=${requestCount}, time=${time}, delta=${time - originalTime}`;
+            const outputLine = `Response success [${response.status}] n=${requestCount}, time=${time}, delta=${time - lastTime}`;
             console.warn(outputLine);
             const newLine = document.createElement("div");
             const newContent = document.createTextNode(outputLine);
             newLine.appendChild(newContent);
 
+            lastTime = time;
             setTimeout(makeRequest, 2000);
             outputElement.appendChild(newLine);
           } else {
+            lastTime = time;
             setTimeout(makeRequest, 2000);
             throw new Error('HTTP error! Status: ' + response.status);
           }