Pack expressions

Option: transforms.packExpressions

What it changes

Merges adjacent compatible variable declarations, combines adjacent expression statements with the comma operator, and moves expressions into a following compatible statement when execution order is preserved.

Before and after

function run() {
  let first = prepare();
  let second = update(first);
  record(first);
  record(second);
  return finish();
}

function run() {
  let first = prepare(),
    second = update(first);
  return record(first), record(second), finish();
}

Configuration

Run this transform by setting transforms.packExpressions to true:

obfuscate.mjs

const output = obfuscate(source, {
  transforms: {
    packExpressions: 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