From the course: Vanilla JavaScript: Web Performance Optimization APIs
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Calculate milestones in the timeline - JavaScript Tutorial
From the course: Vanilla JavaScript: Web Performance Optimization APIs
Calculate milestones in the timeline
- [Instructor] We have already seen that in the navigation time in API we have a lot of performance entries or timings available. While we can get information from each timing alone, it's important to try to analyze the information not just one by one but making some calculations between this navigation matrix. For example if you want to know the time cue first byte so that is from when the request started to when the first byte came to the client. We can take responseStart and fetchStart if we calculate the difference between both matrix we will know exactly the time that was necessary to receive the first byte. There you will have DNS query times, you will have TCP latencies, SSL latency and your server time. So when you have an infrastructure issue you might see that time to first byte is really big. Typically we are looking for a time a time to first byte of around 600 milliseconds on an average connection. Then we have the download part. So here we are going to see the bandwidth…
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