Javascript execution time tool

Show 22 more comments. Sam Watkins 6, 3 3 gold badges 36 36 silver badges 36 36 bronze badges. Owen Owen Timings are not accurate because Date is not intended for this functionality.

I'm going to be bold here and say you should use vsync's example if you want accurate timing. Beware, the getMilliseconds gives you the millisecond fraction of the current second. If you replace getTime with getMilliseconds you can get negative results if you cross a second. AshBlue, we should use window. See stackoverflow. Show 9 more comments. Don't use Date.

Read below. Which means we will get invalid results —like "negative timing"— when the user doesn't have an accurate system time: On Oct , my system clock went haywire and guess what Pacerier Pacerier Just what I was looking for! I want to be able to add several times together, can't really do that with console times. I use Firebug Profile and performance. Doesn't work in my biggest hangup, which is IE7 corporate customers. I don't care about measuring performance in chrome, it's always lightning fast.

This is a better way then console. Show 4 more comments. NicJ NicJ 3, 1 1 gold badge 24 24 silver badges 18 18 bronze badges. I'd say that user timing is not "one other option" for measuring, but the preferred option when the benchmarking is not done on the development machine itself. With your polyfill it works across all browsers. And hiding away the details and boilerplate of performance.

Add a comment. Aaron Hudon 4, 2 2 gold badges 43 43 silver badges 53 53 bronze badges. Varvara Kalinina Varvara Kalinina 1, 17 17 silver badges 26 26 bronze badges. Stefan Mai Stefan Mai Good advice but obviously works only for FF. We often want to compare browser speeds Chrome supports console. Alok Deshwal Alok Deshwal 1, 8 8 silver badges 17 17 bronze badges. You're forcing casting to Number maybe?

Bardelman Exactly It's same as Number new Date. Pang 8, gold badges 82 82 silver badges bronze badges. Achim Koellner Achim Koellner 12 12 silver badges 22 22 bronze badges. Levi Roberts Levi Roberts 1, 3 3 gold badges 19 19 silver badges 43 43 bronze badges.

This is exactly what I was looking for. Thank you! Is there any way to make it universal to use with async functions also? This is great, any way to make it respect Typescript types? Rohit Jaiswal Rohit Jaiswal 3 3 silver badges 5 5 bronze badges. It may help you. Wajeeh Aslam Wajeeh Aslam 71 1 1 silver badge 2 2 bronze badges. While this code snippet may solve the question, including an explanation really helps to improve the quality of your post. Remember that you are answering the question for readers in the future, and those people might not know the reasons for your code suggestion.

Please also try not to crowd your code with explanatory comments, this reduces the readability of both the code and the explanations!

Use it and improve it as you want. Karthikeyan 1, 5 5 silver badges 12 12 bronze badges. Andrew Marin Andrew Marin 1 1 gold badge 12 12 silver badges 15 15 bronze badges. Jonathan Chasteen Jonathan Chasteen 41 4 4 bronze badges. I think you don't need performance. Documentation: Performance measurement APIs.

Mario Varchmin 2, 3 3 gold badges 13 13 silver badges 25 25 bronze badges. If you like the blue color from console. Yu Huang Yu Huang 2, 1 1 gold badge 20 20 silver badges 21 21 bronze badges. To start the timer use console.

Vijay Vijay 70 5 5 bronze badges. Original Size: bytes gzipped bytes uncompressed Compiled Size: bytes gzipped bytes uncompressed Saved While relevant to determining and measuring the efficiency of functions and such, this doesn't really answer the question, and is more of a comment than an answer.

The accepted answer is wrong! Mirza Selimovic Mirza Selimovic 1, 14 14 silver badges 18 18 bronze badges. It's not because of the for loop. A for loop will wait until the last loop until it will go on down your sourcecode. AJAX calls are async. This assumes you have some kind of development or test server running your website's code, which you modify for this purpose and then restore. It is a tool built for testing in a controlled environment, use in production considered harmful.

Note that DeviceTiming will modify your javascript files - it is not reccomended that you use this tool without having a backup of your code. Then start the DeviceTiming server and provide a path to the javascript you wish to test. This will first recursively instrument all the code in the path provided. Then it will start listening at port for beacons from the client code. You can provide a differnt port with -p , see devicetiming -h for more.

To run the tests, visit your development server hosting the instrumented code from each device you wish to test. We use Adobe Edge Inspect in our device lab to perform these tests across all the devices at once. Once you've loaded a page with instrumented code in the browser, it will continuously reload the page to send additional runs to the server. It will continue until you stop it by manually closing or leaving that page.

The instrumentation assumes that the DeviceTiming server can be found at the same hostname as the locations you hit in the browser, if you need to use a different hostname for those beacons, use the --hostname argument with devicetiming server. The first draft of our tests was done by adding a timer to our primary javascript bundle that started on the first line, and ended on the last. For those elements to be processed, the JavaScript execution time must be reduced.

The Lighthouse will report on the total CPU time, script evaluation time, and script parsing time. If the JavaScript execution time is longer than two seconds, then Lighthouse will flag this warning.

If goes longer than 3. To fix this issue and to help reduce JavaScript execution time, one of the first steps is to review your JavaScript code and completely remove any non-critical code.

You can also take advantage of code splitting and distribute JavaScript in smaller files, or chunks. Also, we discussed this earlier in this guide, but preloading key resources, such as JavaScript, can be implemented to download JavaScript earlier, but executed later in the page load process so it does not affect the main-thread tasks.