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Albert Slyvester Duro
Albert Slyvester Duro

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7 tips to measure and analyze JavaScript performance

Performance is an important consideration when developing a website or an app. Nobody wants an app that crashes or a website that doesn't load, especially when the users' waiting time is limited. According to Kissmetrics, 47% of website visitors expect a website to load in less than 2 seconds, and 40% will leave if the loading process takes more than 3 seconds.

Although JavaScript is a fascinating language to work with, it can have a negative impact on the performance of your website. With that in mind, here are seven methods for monitoring the performance of your JavaScript.

  1. Use the performance-related APIs in modern browsers: Many modern browsers provide APIs for measuring and analyzing the performance of JavaScript code, such as the performance object and the console.profile() method.

  2. Use a JavaScript profiler: A JavaScript profiler is a tool that can help identify performance bottlenecks in JavaScript code. Some popular JavaScript profilers include the Chrome DevTools Profiler and the Firefox DevTools Profiler.

  3. Use a performance monitoring service: There are many services available that can help monitor the performance of JavaScript code, such as New Relic and AppDynamics. These services can provide valuable insights into the performance of an application.

  4. Use the browser's performance timeline: The browser's performance timeline can provide detailed information about the performance of an application, including the time it takes for the page to load and the time it takes for individual JavaScript functions to execute.

  5. Measure the real-world performance of an application: It's important to measure the performance of an application in a real-world scenario, rather than just in a controlled environment. This can help identify performance issues that may not be apparent in a controlled setting.

  6. Use synthetic performance tests: Synthetic performance tests are tests that are designed to simulate the performance of an application under specific conditions. These tests can help identify performance issues that may not be apparent in real-world usage.

  7. Use benchmarks: Benchmarks are tests that measure the performance of specific code snippets or algorithms. Comparing the results of benchmarks can help identify performance issues and suggest ways to improve the performance of JavaScript code.


It is critical to strike a balance between code readability and optimization. Computers interpret the code, but we need to ensure that it can be maintained in the future by ourselves or others, so it must be understandable.

Remember that performance should always be considered, but it should never be prioritized over debugging and adding functionalities.

Sometimes, people really just care about what works.

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