Updates to assignments

Option: transforms.updateToAssignment

What it changes

Rewrites eligible numeric update expressions as compound assignments. Postfix updates stay unchanged when their original value is used.

let i = 0;
i++;
arr[++i] = 1;
let n = 5n;
n++;

let i = 0;
i += 1;
arr[i += 1] = 1;
let n = 5n;
n++;

Run this transform by setting transforms.updateToAssignment to true:

obfuscate.mjs

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

Open the TypeScript implementation on GitHub.

Review behavior checks and cases this transform leaves alone.

Last modified on August 26, 2026