Response Time

Response time measures the speed at which a system processes a request and returns a result, and for user-facing applications, is directly related to user experience.

For example, in a web application, response time is the duration between clicking a link and the page fully loading. This can be affected by various factors such as network latency, server load, and database performance.

In JavaScript, you can measure response time using the built-in performance API. For instance, to calculate the response time for an HTTP request, you can use the following code snippet:

const start = performance.now();
fetch('https://api.example.com/data')
  .then(response => response.json())
  .then(data => {
    const end = performance.now();
    const responseTime = end - start;
    console.log(`Response time: ${responseTime} milliseconds`);
  });

For more complex application, you can use distributed tracing with OpenTelemetry to measure the response time of various request, both on the client and server-side.