Collapse single-use temporaries

Option: transforms.collapseSingleUseTemps

What it changes

Replaces eligible single-use temporary bindings with their values and removes the declarations.

var _t;
if (cond) { _t = 1; } else { _t = 2; }
return _t;

if (cond) { return 1; } else { return 2; }

Run this transform by setting transforms.collapseSingleUseTemps to true:

obfuscate.mjs

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

Open the TypeScript implementation on GitHub.

Review behavior checks and cases this transform leaves alone.

Last modified on August 26, 2026