if return proposal

Field	Value
Proposal	if return <expression>;
Authors	@NookieGrey
Champion	Seeking champion(s)
Stage	0
Process	TC39 process document

Status

This repository contains an early Stage 0 draft. The main immediate goal is to find TC39 champion(s) to refine scope, syntax, and semantics for potential Stage 1 presentation.

Motivation

In JavaScript code, a common early-return pattern repeats often:

const value = compute();
if (value) return value;

The proposal introduces a compact statement form for this exact pattern.

Proposal shape

Proposed syntax:

if return expression;

Intended behavior:

1. Evaluate expression once.
2. If the result is truthy, return that result from the current function.
3. Otherwise continue execution.

Equivalent desugaring model:

const _temp = expression;
if (_temp) return _temp;

_temp above is explanatory only; no user-visible binding is created.

Examples

Basic use

function getCachedOrNull(key) {
  if return cache.get(key);
  return null;
}

Chained fallbacks

function getGoodsPrice(id) {
  if return getPrice(id);
  if return getLastPrice(id);
  return 0;
}

Single-evaluation guarantee

function read() {
  if return maybeExpensiveRead();
  return "default";
}

maybeExpensiveRead() is evaluated once.

Non-goals

• This proposal does not add an else branch to if return.
• This proposal does not change JavaScript truthiness rules.
• This proposal is not currently an expression-form construct.

Open design questions

1. Is if return the best keyword order, or should alternative spellings be considered?
2. Should this form be allowed everywhere return is allowed, or in a narrower context?
3. Are there parsing or readability concerns with ASI and statement boundaries?
4. Should tooling enforce/forbid this shorthand in specific style profiles?

Why built-in syntax?

Userland helpers cannot short-circuit with function-local return. This pattern can only be made concise with syntax.

Champion request

Looking for TC39 champion(s) to help with:

1. Stage 1 viability assessment.
2. Syntax and grammar risk review.
3. Agenda strategy for initial TC39 discussion.
4. Consensus-building on alternatives.

See /docs/champion-outreach.md for a concise outreach message.

Prototype and experiments

Not required for Stage 0, but useful for feedback quality:

1. A Babel prototype transform (optional).
2. ESLint/parser experiment support (optional).
3. Example corpus rewrite to measure readability impact.

Babel proof-of-concept

This repository includes a minimal Babel prototype in /transpiler/babel-plugin-if-return.js.

Run it on the sample:

npm install
npm run transpile:example

Input:

• /examples/input-if-return.js

Output:

• /examples/output-if-return.js

Current PoC limitation: custom syntax is recognized only for standalone single-line statements in the form if return <expression>;.

Specification draft

Early spec text lives in /spec.emu and is intentionally minimal at Stage 0.