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Load Testing a Single-Page Application (SPA)

Comprehensive guide on load testing your SPA with the LoadForge platform

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Single-page applications (SPAs) have become a popular choice in modern web development. With the dynamic retrieval of data, SPAs offer a seamless user experience as there is no need for full page refreshes. This poses some unique challenges for load testing, but with LoadForge, the process is made simple and efficient.

Understanding Single-Page Applications (SPA)

A Single-Page Application (SPA) is a type of web application that serves a singular web page. Instead of loading new pages, SPAs dynamically rewrite the current page with new data fetched from the server.

Key Characteristics of SPAs:

  1. No Page Refresh: In SPAs, full-page refreshes are never needed.
  2. Dynamic Content: All required HTML, JavaScript, and CSS are either loaded initially or added dynamically as necessary, usually based on user interactions.

Steps to Load Test an SPA with LoadForge

1. User Simulation

The goal of load testing is to mimic real-world users interacting with your site. In the context of an SPA:

  • New users will typically request the initial page and any essential JavaScript resources.
  • Subsequent interactions, like browsing content, logging in, or checking out, usually involve JSON API requests.

2. Capture the Requests

These JSON API requests are vital for a realistic load test. To capture them:

  • Use your browser's Developer Tools (usually accessible with F12 or right-click -> Inspect).
  • Alternatively, use the Record Your Browser feature on LoadForge. This handy feature allows you to record interactions with your SPA and then generates a test script for you.

3. Leverage the LoadForge Wizard

LoadForge's wizard simplifies the load testing process:

  • It automatically fetches all page dependencies, ensuring your tests start from a "fully loaded" SPA state.
  • Once you have the generated or hand-written script, setting up your load test becomes straightforward. Specify the number of virtual users, their average wait time between requests, and the total test duration.

With these configurations in place, you're all set to run your test on LoadForge!

Locust Test Example

Did you know? LoadForge is powered by locust.io. This means if you're an existing locust user, you can seamlessly use your scripts with LoadForge. For an enhanced testing experience, consider importing your locust script to LoadForge.

Example Locust Script for an SPA Load Test

To aid in your understanding, here's an example locust script tailored for SPAs:

from locust import HttpUser, task, between

class SPATestUser(HttpUser):
    wait_time = between(5, 15)

    def load_spa_page(self):

    def simulate_user_interaction(self):
        headers = {"Content-Type": "application/json"}
        data = {
            # Your JSON data mimicking user action, e.g. login details
        self.client.post("/path_to_api_endpoint", headers=headers, json=data)

# You can add more tasks to simulate different user actions.

Remember, the more accurately your script simulates real-world user behavior, the more valuable your load test results will be!

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