1.0.2 • Published 5 months ago
with-defer-es v1.0.2
with-defer-es
Great thanks to James M. Lay
Golang style I have since found a paradigm that plays better with the way I personally use javascript. It's based on golang's defer statement. You simply wrap your code in a "scope" IIFE, and when that function is left for any reason, the deferred expressions are executed in reverse order, awaiting any promises. by James M. Lay https://stackoverflow.com/a/59634819
Usage:
import withDefer from 'with-defer-es'
// or if you are still using commonjs
// const withDefer = await import( 'with-defer-es').then(e=>e.default)
withDefer(async (defer) => {
const s = await openStream();
defer(() => closeStream(s));
const db = new DBConnection();
defer(() => db.close());
throw new Error("oh snap"); // could also be return
// will call db.close() then closeStream(s)
});index.spec.ts
import withDefer from ".";
import {vi, it, expect } from "vitest";
it("calls releases in correctly order", async () => {
const stdout = [] as string[];
const stderr = [] as string[];
console.log = (msg: string) => {
stdout.push(String(msg));
console.info(msg);
};
console.error = (msg: string) => {
stderr.push(String(msg));
console.warn(msg);
};
await withDefer((defer) => {
console.log("create resource A");
defer(() => console.log("release resource A"));
console.log("create resource B");
defer(() => {
console.log("release resource B");
throw new Error("but got error on releasing resource B");
});
throw new Error("oops, something get error");
console.log("create resource C");
defer(() => console.log("release resource C"));
}).catch((error) => {
console.error(error);
});
expect(stdout.join("\n")).equal(
`
create resource A
create resource B
release resource B
release resource A
`.trim()
);
});Dev
pnpm install
pnpm test
pnpm build