Remove unused code

Option: transforms.removeUnusedCode

What it changes

Removes unused declarations and side-effect-free expression statements until no further code becomes unused.

function foo() { return "foo"; }
function bar() { return "bar"; }
var unused = 1;
foo();

function foo() { return "foo"; }
foo();

Run this transform by setting transforms.removeUnusedCode to true:

obfuscate.mjs

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

Open the TypeScript implementation on GitHub.

Review behavior checks and cases this transform leaves alone.

Last modified on August 26, 2026