javascript - Google Closure 编译器不压缩字符串值？

Question

有这样的东西:

(function ($, window, document, undefined) {
    'use strict';
    $.fn.demo = function (options) {

        var active = "active";
        var section = ".bb-demo";

        $(section).addClass(active);
        $(section).addClass(active);
        $(section).addClass(active);
        $(section).addClass(active);

    };
})(jQuery, window, document);

Closure Simple mode结果为 200 字节:

(function(a,b,c,d){a.fn.demo=function(b){a(".bb-demo").addClass("active");a(".bb-demo").addClass("active");a(".bb-demo").addClass("active");a(".bb-demo").addClass("active")}})(jQuery,window,document);

同时 YUI compressor结果为 169 字节:

(function(c,b,a,d){c.fn.demo=function(e){var g="active";var f=".bb-demo";c(f).addClass(g);c(f).addClass(g);c(f).addClass(g);c(f).addClass(g)}})(jQuery,window,document);

难道没有办法在 Closure 中也压缩那些字符串变量吗？ 为什么不这样做？ 是因为在性能方面有更好的结果吗？

Answer 1

这包含在 Closure Compiler FAQ 中。 https://github.com/google/closure-compiler/wiki/FAQ#closure-compiler-inlined-all-my-strings-which-made-my-code-size-bigger-why-did-it-do-that

Closure Compiler assumes that you are using gzip compression. If you do not, you should. Configuring your server to gzip your code is one of the most effective and easiest optimizations that you can possibly do. The gzip algorithm works by trying to alias sequences of bytes in an optimal way. Aliasing strings manually almost always makes the compressed code size bigger, because it subverts gzip's own algorithm for aliasing. So Closure Compiler will (almost) always inline your strings when it can, because that will make your compressed code smaller.