Fold built-in methods

Option: transforms.foldBuiltinMethods

What it changes

Replaces eligible built-in calls and property reads with smaller equivalent expressions or constants.

Math.pow(2, 3);
Array.of(1, 2, 3);
"abc".toUpperCase();
Math.PI;
parseInt("0x1F", 16);

8;
[1, 2, 3];
"ABC";
3.141592653589793;
31;

Run this transform by setting transforms.foldBuiltinMethods to true:

obfuscate.mjs

const output = obfuscate(source, {
  transforms: {
    foldBuiltinMethods: true,
  },
})

Open the TypeScript implementation on GitHub.

Review behavior checks and cases this transform leaves alone.

Last modified on August 26, 2026