Having nameCache controls

• Operating System: Windows
• Node Version: 13.5.0
• NPM Version: 6.13.4
• webpack Version: 4.41.2
• terser-webpack-plugin Version: 3.0.2

Feature Proposal

What about adding nameCache option? I haven't used it before, but as documentation suggests we should be able to tell terser to use js object (or it would be more correct to call it dictionary) to map names (as I guess variables, classes, functions) to predefined, new, minified names instead of just renaming them to alphabetically smallest, nonempty, available string.

To say it simply, I'm asking to bring this somehow possible in webpack plugin too:

var cacheFileName = "/tmp/cache.json";
var options = {
    mangle: {
        properties: true,
    },
    nameCache: JSON.parse(fs.readFileSync(cacheFileName, "utf8"))
};
fs.writeFileSync("part1.js", Terser.minify({
    "file1.js": fs.readFileSync("file1.js", "utf8"),
    "file2.js": fs.readFileSync("file2.js", "utf8")
}, options).code, "utf8");
fs.writeFileSync("part2.js", Terser.minify({
    "file3.js": fs.readFileSync("file3.js", "utf8"),
    "file4.js": fs.readFileSync("file4.js", "utf8")
}, options).code, "utf8");
fs.writeFileSync(cacheFileName, JSON.stringify(options.nameCache), "utf8");

And this code in my opinion also saves new names cache to same file too. I think this is impossible now in terser webpack plugin.

Feature Request: Add ability/option to bind json file as name cache.

Feature Use Case

<! -- problem -->

Easiest use case would be, I need to build application (currently in angular) which has more than two files bundled (let's assume 3). First and second files both have dependency on third.

Now if I build only first file, after minification first minified file will have for example console.log(thirdModule.thirdModuleVariable) transformed into console.log(thirdModule.a).

But if I only build second file or if I build whole project thirdModule's thirdModuleVariable may become b.

</!-- problem -->

What I want in the end is that in angular application I have appModule => [firstLazyModule, secondLazyModule, thirdLazyModule]. Now I will build whole app, then I will comment out other two modules and build only appModule => [firstLazyModule] (because building all three of them takes too long and I have only changed code in firstLazyModule, after building app with only one module, I will take generated module bundle and I will replace corresponding module file in the firstly generated directory with this new module bundle file.

This whole thing works if I don't use terser plugin, but doesn't work with terser because of the problem I have provided. If I'll have nameCache file in the project, each time I build app it will generate and use in next builds same minified variable names and replacing modules will still work.

I hope we can work this out. Thank you in advance.

Start by tracing the plugin's existing option handling and its Terser invocation; the issue does not name specific files or tests. Use the described multi-bundle Angular scenario to verify that a persisted nameCache can be supplied and updated, and that separate builds preserve compatible minified names.