Comparison of JavaScript compression methods

While creating the build system for our Java web application, I set out to do some benchmarking on some of the different JavaScript compression methods. When our project builds, I configured our Ant build script to create three different version of our JavaScript files; full source, minified (comments and whitespace removed), and packed (compressed).

I also configured Tomcat to use gzip compression and then ran six different test, the three version of our JavaScript files without gzip compression and the three versions with gzip compression.

I measured the load time and size using FireBug from within Firefox and recorded the following results:

Full Source Minified Packed
Without GZIP 167 KB | 329ms 95 KB | 281ms 70 KB | 313ms
With GZIP 67 KB | 297ms 48 KB | 219ms 47 KB | 312ms

Although my “tests” are very informal, I think that it is clear that the minified version with GZIP server compression offers the best results. It is only slightly larger than the packed version in size, but it loads almost 30% faster (due to the overhead of decompressing the packed version).

7 thoughts on “Comparison of JavaScript compression methods”

  1. @Peter – I prefaced my response with “gzip, as mentioned here, refers to…”. I’ll change last sentence to be more clear, but again, I was speaking in terms of server compression not physical file compression.

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