JS. Compression and obfuscation.

One day, the front-end began code optimization. I am responsible for learning from you.

 

About code compression.

 

1. Compression tool classification.

 

Class 1: File compression. Gzip. Compress several files into a gz package. You can increase the speed when downloading code. Official website. This has been available for a long time and is still in use ~

 

Another type: remove the blank comment of the file. Such as JSMin, YUI Compressor, and Google Closure Compiler. There may be Dojo Compressor and so on.

 

2. a few details.

 

A. JSMin. No obfuscation is processed. (Obfuscation, simply put, refers to replacing the name of the variable function you define with a letter, which is shorter and is not known by others. Of course, obfuscation is not that simple ..)

 

Usage: JSMin <uncompressor. js> compressor. js ()

Note: js files are preferably in ASCII or UTF-8 format. But we are generally UTF-8 Oh.

The JSMin operation is irreversible. Save the source file and standardize the code. JSLint.

 

 

B. YUI Compressor. Based on Java (JRE.> 1.4 ). But it is better than JSMin compression. YUI can also compress CSS files.

 

Principle: Remove redundant spaces; shorten the variable name for JS; optimize the 0 value attribute value for CSS and optimize the color value (but not as good as CSSTidy: Support merging related attributes .)

Usage: java-jar yuicompressor-2.4.2.jar in. js-o out. js ()

Java-jar yuicompressor-2.4.1.jar -- nomunge -- preserve-semi -- disable-optimizations in. js-o out. js (no obfuscation, no semicolon, No optimization ..)

Java-jar yuicompressor-2.4.1.jar -- charset UTF-8 in. js-o out. js (UTF-8 encoding can be specified)

 

Others. You can refer to this remark. Some principles. (This article involves some knowledge points. For details, see the high-performance JS book .)

 

C. Google Closure Compiler. For details, see. The PPT of Yubo.