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JavaScript Dead Code Analyzer

Paste a JS bundle and find top-level functions with no static reference anywhere in the file — a heuristic reachability scan, not a certainty.

scienceHeuristic only. A function marked "likely unused" can still be called dynamically — through obj[computedName](), eval, new Function(...), or Function.prototype.call/apply on a reference chosen at runtime — in ways this static scan cannot see. Verify by hand before deleting anything.JavaScript source
Comma-separated function names to treat as reachable roots even if no reference to them is found elsewhere in the file.

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What this actually checks

This tool parses your JavaScript with acorn and builds a reference graph: every top-level function declaration (or const x = function(){} / const x = () => {} at the top level) becomes a node, and every place its name appears elsewhere as an identifier becomes an edge. It then computes which of those functions are reachable from a set of roots — code that runs unconditionally when the file loads: statements directly at the top level, the body of an immediately-invoked function expression (IIFE), anything assigned to module.exports / exports.x / window.x / globalThis.x, and any entry-point names you type in yourself. Everything reachable from a root, transitively, is kept; everything left over is reported.

Read this before you trust a finding

A function this tool calls "likely unused" may still be genuinely used. Static analysis cannot see through:

  • Dynamic dispatch — obj[someComputedName](), table[key]() — the property name is only known at runtime.
  • eval and new Function(...) — code built from a string is invisible to an AST walk.
  • Reflection — fn.call(...), fn.apply(...) on a reference chosen dynamically, or Object.keys(obj).forEach(k => obj[k]()).

Every finding is phrased as "no static reference found", never as a fact. Treat this as a lead worth checking by hand, not a verdict — especially before deleting anything.

How to use it

Paste or load a .js file's contents into the editor. If you already know the name of your bundle's real entry function (the one your HTML calls, or a framework calls for you), type it into the entry points field so it — and everything it transitively touches — is anchored as reachable even if nothing in the file itself references it by name.

The summary shows total top-level functions, how many are reachable, and how many have no static reference. Each finding lists the function name and its line number. A separate, collapsed list shows the full reachable set with a short reason for each — an entry point, an export, a call inside an IIFE, or a reference found inside another reachable function.

Nothing you paste leaves your browser.