Prevent UglifyJS from changing function arguments' names

Question

When deploying my app on a test server, I came with an error where UglifyJS did change a npm dependency module's functions arguments, where the names of these arguments are important; some functions are called dynamically and I am using function-arguments to map certain values to certain function arguments based on their corresponding names.

Is it possible to tell UglifyJS to skip certain modules, or files, etc.?

Answer 1

According to the documentation you can use mangle options to for that:

• mangle (default true) — pass false to skip mangling names, or pass an object to specify mangling options

Object options:

• except - pass an Array of identifiers that should be excluded from mangling
• toplevel — mangle names declared in the toplevel scope (disabled by default).
• eval — mangle names visible in scopes where eval or with are used (disabled by default).
• keep_fnames -- default false. Pass true to not mangle function names. Useful for code relying on Function.prototype.name.

---

//tst.js
var globalVar;
function funcName(firstLongName, anotherLongName)
{
  var myVariable = firstLongName +  anotherLongName;
}

UglifyJS.minify("tst.js").code;
// 'function funcName(a,n){}var globalVar;'

UglifyJS.minify("tst.js", { mangle: { except: ['firstLongName'] } }).code;
// 'function funcName(firstLongName,a){}var globalVar;'

UglifyJS.minify("tst.js", { mangle: { toplevel: true } }).code;
// 'function n(n,a){}var a;'

I tried to find an option to mangle the function names and skip mangling the arguments and didn't fun that so far (not saying there isn't...)