Hoist variables

Option: transforms.hoistVariables

What it changes

Moves var declarations to the beginning of their containing function or program without moving initializer evaluation.

function f() {
  var x = 1;
  if (c) {
    var y = g();
  }
  return x + y;
}

function f() {
  var y, x;
  x = 1;
  if (c) {
    y = g();
  }
  return x + y;
}

Run this transform by setting transforms.hoistVariables to true:

obfuscate.mjs

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

Open the TypeScript implementation on GitHub.

Review behavior checks and cases this transform leaves alone.

Last modified on August 29, 2026