Function tryCatch

Package: @litert/utils-flow-controlSource: packages/partials/flow-control/src/Functions/TryCatch.ts

An expression-style try-catch[-finally] statement. Instead of the try { ... } catch { ... } syntax (which cannot be used as an expression), tryCatch wraps the same logic as a function call and returns the resulting value. It correctly handles all combinations of synchronous and asynchronous try, catch, and finally bodies — and automatically returns a Promise if any of the involved functions is asynchronous.

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Import

import { tryCatch } from '@litert/utils-flow-control';

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Signature

function tryCatch<TOk, TErr = never, TFinal extends void | Promise<void> = void>(
    opts: ITryCatchOptions<TOk, TErr, TFinal>
): ITryCatchResult<TOk, TErr, TFinal>;

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Parameters

Parameter	Type	Description
opts	ITryCatchOptions<TOk, TErr, TFinal>	Options object with try, catch, and optional finally bodies. See ITryCatchOptions

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Return Value

The return value of the try body, or the return value of the catch body if an error was thrown. If any body is asynchronous, a Promise is returned automatically.

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Error Handling

If the catch body or finally body throws, the error propagates to the caller normally, just as in a standard try-catch-finally statement.

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Scoped Types

Interface ITryCatchOptions

Source: TryCatch.ts

import type { ITryCatchOptions } from '@litert/utils-flow-control';

Options for the tryCatch function, describing the bodies of the try, catch, and optionally finally clauses.

Property	Type	Required	Description
try	() => TOk	Yes	The try body. May be synchronous or asynchronous.
catch	(e: unknown) => TErr	Yes	The catch body. Receives the thrown error. May be synchronous or asynchronous. The finally clause still runs even if catch throws.
finally	() => TFinal	No	The finally body. Must be synchronous. Runs after try or catch completes regardless of outcome. To avoid error-handling complexity, ensure this function does not throw.

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Type Alias ITryCatchResult

Source: TryCatch.ts

import type { ITryCatchResult } from '@litert/utils-flow-control';

A utility type that computes the exact return type of tryCatch based on the inferred types of TOk, TErr, and TFinal.

• If any of TOk, TErr, or TFinal is a Promise, the result is a Promise of the appropriate union type.
• If all three are synchronous, the result is a synchronous union type.

type ITryCatchResult<TOk, TErr, TFinal> = /* complex conditional type */;

You rarely need to reference this type directly; TypeScript infers it automatically from the arguments you pass to tryCatch.

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Examples

import { tryCatch } from '@litert/utils-flow-control';

// Synchronous
const result = tryCatch({
    try: () => JSON.parse('{"ok":true}'),
    catch: () => ({ ok: false }),
});
console.log(result); // { ok: true }

// Asynchronous
const data = await tryCatch({
    try: async () => fetch('/api/data').then(r => r.json()),
    catch: (e) => { console.error(e); return null; },
    finally: () => { console.log('done'); },
});