Const and let to var

Option: transforms.constLetToVar

What it changes

Converts eligible let and const declarations to var, renaming bindings when needed to avoid hoisting conflicts. Loop bindings stay unchanged when conversion would alter iteration behavior.

Before and after

function f() {
  const x = 1;
  return x;
}

function f() {
  var x = 1;
  return x;
}

Configuration

Run this transform by setting transforms.constLetToVar to true:

obfuscate.mjs

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

View the implementation

Open the TypeScript implementation on GitHub.

Read the behavior tests

Review behavior checks and cases this transform leaves alone.

Last modified on August 26, 2026

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Reference

Support

What it changes

Before and after

Configuration

View the implementation

Read the behavior tests

​What it changes

​Before and after

​Configuration

View the implementation

Read the behavior tests

What it changes

Before and after

Configuration