Adding Go's Defer to the TypeScript Compiler
I wanted to see how difficult it would be to add Go's defer statement to the TypeScript compiler, but by the time I finished I was convinced it probably shouldn't exist.In Go, the defer statement delays the execution of a function until the surrounding function finishes. You might use try/finally, like:async function readFile(path: string) { await sema.acquire(); try { // ... use resource } finally { sema.release(); }}But that's kinda ugly.For fun, we can hack in a defer statement to the TypeScript compiler and get Go-like semantics. This matches Go's semantics, where the function value, receiver, and arguments are all evaluated when execution reaches the defer statement.Any function that contains at least one defer gets a small stack, and each reached defer statement pushes a closure onto that stack.
- ▪I wanted to see how difficult it would be to add Go's defer statement to the TypeScript compiler, but by the time I finished I was convinced it probably shouldn't exist.In Go, the defer statement delays the execution of a function until the
- ▪You might use try/finally, like:async function readFile(path: string) { await sema.acquire(); try { // ... use resource } finally { sema.release(); }}But that's kinda ugly.For fun, we can hack in a defer statement to the TypeScript compiler
- ▪This matches Go's semantics, where the function value, receiver, and arguments are all evaluated when execution reaches the defer statement.Any function that contains at least one defer gets a small stack, and each reached defer statement p
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| Original publisher | Healeycodes |
| Canonical URL | https://healeycodes.com/adding-defer-to-the-typescript-compiler |
| Publication time | Sun, 02 Aug 2026 20:12:39 +0000 |
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I wanted to see how difficult it would be to add Go's defer statement to the TypeScript compiler, but by the time I finished I was convinced it probably shouldn't exist.In Go, the defer statement delays the execution of a function until the surrounding function finishes. It's most commonly used to keep resource acquisition and cleanup together, like acquiring a semaphore:func withSemaphore(ctx context.Context, sem *semaphore.Weighted) error { if err := sem.Acquire(ctx, 1); err != nil { return err } defer sem.Release(1) // ... protected work return nil}TypeScript doesn't have a strict equivalent of defer. You might use try/finally, like:async function readFile(path: string) { await sema.acquire(); try { // ...
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