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JSMeter: Measuring JavaScript Web Applications

The goal of JSMeter is to measure the runtime behavior of JavaScript programs. Our ultimate goal is to improve the quality of JavaScript engine implementations.


Can you tell the JavaScript benchmark from the Real Web App?  



JavaScript is widely used in web-based applications and is increasing popular with developers. So-called ”browser wars” in recent years have focused on JavaScript performance, specifically claiming comparative results based on benchmark suites such as SunSpider and V8. In this paper we evaluate the behavior of JavaScript web applications from commercial websites and compare this behavior with the benchmarks.

We measure three specific areas of JavaScript runtime behavior: 1) functions and code; 2) heap-allocated objects and data; 3) events and handlers. We find that the benchmarks are not representative of many real websites and that conclusions reached from measuring the benchmarks may be misleading.

Specific examples of such misleading conclusions include the following: that web applications have many loops, that non-string objects in web applications are extremely short-lived, and that web applications handle few events.

We hope our results will convince the JavaScript community to develop and adopt benchmarks that are more representative of real web applications.

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Papers and presentations 

Executive summary  3 pages 
"JSMeter: Measuring JavaScript Behavior in the Wild", Paruj Ratanaworabhan, Benjamin Livshits, David Simmons, and Benjamin Zorn, MSR-TR-2010-8, January 2010 (short technical report) 17 pages 
"JSMeter: Characterizing Real-World Behavior of JavaScript Programs", Paruj Ratanaworabhan, Benjamin Livshits, David Simmons, and Benjamin Zorn, MSR-TR-2009-173, December 2009 (long technical report) 49 pages 

Presentation: "JSMeter: Characterizing the Behavior of JavaScript Web Applications" (pdf), February 2010  

40 slides