init

.gitignore

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+# Based on https://raw.githubusercontent.com/github/gitignore/main/Node.gitignore
+
+# Logs
+
+logs
+_.log
+npm-debug.log_
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+.pnpm-debug.log*
+
+# Caches
+
+.cache
+
+# Diagnostic reports (https://nodejs.org/api/report.html)
+
+report.[0-9]_.[0-9]_.[0-9]_.[0-9]_.json
+
+# Runtime data
+
+pids
+_.pid
+_.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+
+lib-cov
+
+# Coverage directory used by tools like istanbul
+
+coverage
+*.lcov
+
+# nyc test coverage
+
+.nyc_output
+
+# Grunt intermediate storage (https://gruntjs.com/creating-plugins#storing-task-files)
+
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+
+bower_components
+
+# node-waf configuration
+
+.lock-wscript
+
+# Compiled binary addons (https://nodejs.org/api/addons.html)
+
+build/Release
+
+# Dependency directories
+
+node_modules/
+jspm_packages/
+
+# Snowpack dependency directory (https://snowpack.dev/)
+
+web_modules/
+
+# TypeScript cache
+
+*.tsbuildinfo
+
+# Optional npm cache directory
+
+.npm
+
+# Optional eslint cache
+
+.eslintcache
+
+# Optional stylelint cache
+
+.stylelintcache
+
+# Microbundle cache
+
+.rpt2_cache/
+.rts2_cache_cjs/
+.rts2_cache_es/
+.rts2_cache_umd/
+
+# Optional REPL history
+
+.node_repl_history
+
+# Output of 'npm pack'
+
+*.tgz
+
+# Yarn Integrity file
+
+.yarn-integrity
+
+# dotenv environment variable files
+
+.env
+.env.development.local
+.env.test.local
+.env.production.local
+.env.local
+
+# parcel-bundler cache (https://parceljs.org/)
+
+.parcel-cache
+
+# Next.js build output
+
+.next
+out
+
+# Nuxt.js build / generate output
+
+.nuxt
+dist
+
+# Gatsby files
+
+# Comment in the public line in if your project uses Gatsby and not Next.js
+
+# https://nextjs.org/blog/next-9-1#public-directory-support
+
+# public
+
+# vuepress build output
+
+.vuepress/dist
+
+# vuepress v2.x temp and cache directory
+
+.temp
+
+# Docusaurus cache and generated files
+
+.docusaurus
+
+# Serverless directories
+
+.serverless/
+
+# FuseBox cache
+
+.fusebox/
+
+# DynamoDB Local files
+
+.dynamodb/
+
+# TernJS port file
+
+.tern-port
+
+# Stores VSCode versions used for testing VSCode extensions
+
+.vscode-test
+
+# yarn v2
+
+.yarn/cache
+.yarn/unplugged
+.yarn/build-state.yml
+.yarn/install-state.gz
+.pnp.*
+
+# IntelliJ based IDEs
+.idea
+
+# Finder (MacOS) folder config
+.DS_Store

README.md

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+# Grip
+
+Simplified result/error handling for JavaScript.
+Grip always returns a consistent call result ready to be handled.
+It makes the control flow similar to that of Golang, but doesn't force you to make additional null checks or create transitional variables to hold error results.
+
+## Install
+
+```bash
+bun add github:nesterow/grip
+```
+
+## Usage
+
+The `grip` function accepts a function or a promise and returns a result with return value and status.
+The result can be hadled as either an object or a tuple.
+
+```javascript
+import { grip } from '@nesterow/grip';
+```
+
+## Handle result as an object:
+
+The result can be handled as an object: `{value, status, Ok(), Fail(), Of(type)}`
+
+```javascript
+const fetchResult = await grip(
+  fetch('https://api.example.com')
+);
+
+if (fetchResult.Fail()) {
+    handleErrorProperly();
+    return;
+}
+
+const jsonResult = await grip(
+  res.value.json()
+);
+
+if (jsonResult.Of(SyntaxError)) {
+    handleJsonParseError();
+    return;
+}
+
+```
+
+## Handle result as a tuple:
+
+The result can also be received as a tuple if you want to handle errors in Go'ish style:
+
+```javascript
+const [response, fetchStatus] = await grip(
+  fetch('https://api.example.com')
+);
+if (fetchStatus.Fail()) {
+    handleErrorProperly();
+    return;
+}
+
+const [json, parseStatus] = await grip(
+  response.json()
+);
+if (parseStatus.Of(SyntaxError)) {
+    handleJsonParseError();
+    return;
+}
+```
+
+## License
+MIT

grip.test.ts

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+import { test, expect } from "bun:test";
+import { grip } from "./grip";
+
+test("Promise", async () => {
+  const [result, status] = await grip(Promise.resolve("ok"));
+  expect(result).toBe("ok");
+  expect(status.Ok()).toBe(true);
+});
+
+test("Promise.reject", async () => {
+  const [result, status] = await grip(() =>
+    Promise.reject(new Error("not ok")),
+  );
+  expect(status.Ok()).toBe(false);
+  expect(status.message).toBe("not ok");
+  expect(result === null).toBe(true);
+});
+
+test("() => Promise", async () => {
+  const [result, status] = await grip(() => Promise.resolve("ok"));
+  expect(result).toBe("ok");
+  expect(status.Ok()).toBe(true);
+});
+
+test("() => value", () => {
+  const [result, status] = grip(() => "ok");
+  expect(result).toBe("ok");
+  expect(status.Ok()).toBe(true);
+});
+
+test("() => throw", async () => {
+  const [_, status] = grip(() => {
+    if (1) throw "not ok";
+  });
+  expect(status.Ok()).toBe(false);
+  expect(status.message).toBe("not ok");
+});
+
+test("Result { 0, 1, value, Ok(), Fail() }", async () => {
+  const result = grip(() => {
+    if (1) throw "not ok";
+  });
+  expect(result.Ok()).toBe(false);
+  expect(result.value === null).toBe(true);
+  expect(result.status.message).toBe("not ok");
+});
+
+test("fetch err", async () => {
+  const [result, status] = await grip(fetch("https://localhost:30012"));
+  expect(status.Ok()).toBe(false);
+  expect(result === null).toBe(true);
+  expect(status.Of(Error)).toBe(true);
+});
+
+test("fetch json", async () => {
+  const [result, fetchStatus] = await grip(() =>
+    fetch("https://google.com/404"),
+  );
+  expect(fetchStatus.Ok()).toBe(true);
+  expect(result.ok).toBe(false);
+  const [json, jsonStatus] = await grip(result.json());
+  expect(jsonStatus.Ok()).toBe(false);
+  expect(jsonStatus.Of(SyntaxError)).toBe(true);
+  expect(json === null).toBe(true);
+});

grip.ts

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+interface Status extends Error {
+  Ok(): boolean;
+  Fail(): boolean;
+  Of(cls: any): boolean;
+}
+
+export class Err extends Error {
+  Ok() {
+    return false;
+  }
+  Fail() {
+    return true;
+  }
+  Of(cls: any) {
+    return this.cause instanceof cls || this instanceof cls;
+  }
+  static fromCatch(error: any) {
+    const e = new Err(typeof error === "string" ? error : error.message);
+    e.cause = error;
+    e.stack = error.stack;
+    return e;
+  }
+}
+
+export class Ok extends Error {
+  Ok() {
+    return true;
+  }
+  Fail() {
+    return false;
+  }
+  Of(cls: any) {
+    return this instanceof cls;
+  }
+}
+
+interface IResult<T> {
+  0: T;
+  1: Status;
+  value: T;
+  status: Status;
+  Of(cls: any): boolean;
+  Ok(): boolean;
+  Fail(): boolean;
+}
+
+class Result<T> extends Array<T | Status> implements IResult<T> {
+  0: T;
+  1: Status;
+  constructor(result: T, status: Status) {
+    super(2);
+    this[0] = result;
+    this[1] = status;
+  }
+  get value() {
+    return this[0];
+  }
+  get status() {
+    return this[1];
+  }
+  Ok() {
+    return (this[1] as Status).Ok();
+  }
+  Fail() {
+    return (this[1] as Status).Fail();
+  }
+  Of(impl: any) {
+    return (this[1] as Status).Of(impl);
+  }
+}
+
+type Unwrap<T> =
+  T extends Promise<infer U>
+    ? U
+    : T extends (...args: any) => Promise<infer U>
+      ? U
+      : T extends (...args: any) => infer U
+        ? U
+        : T;
+
+export type SafeResult<T> =
+  T extends Promise<any>
+    ? Promise<Result<Unwrap<T>>>
+    : T extends () => Promise<any>
+      ? Promise<Result<Unwrap<T>>>
+      : Result<Unwrap<T>>;
+
+export function grip<T>(action: T): SafeResult<T> {
+  if (action instanceof Promise) {
+    return promise<T>(action) as SafeResult<T>;
+  }
+  try {
+    const result = (action as any)();
+    if (result instanceof Promise) {
+      return promise<T>(result) as SafeResult<T>;
+    }
+    return new Result<T>(result, new Ok()) as SafeResult<T>;
+  } catch (err: any) {
+    return new Result<T>(null as any, Err.fromCatch(err)) as SafeResult<T>;
+  }
+}
+
+const promise = <T>(result: Promise<T>) => {
+  return result
+    .then((res) => new Result(res, new Ok()))
+    .catch((err) => new Result(null, Err.fromCatch(err))) as Promise<Result<T>>;
+};

mod.ts

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+export * from "./grip.ts";

package.json

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+{
+  "name": "@nesterow/follow",
+  "module": "grip.ts",
+  "type": "module",
+  "devDependencies": {
+    "@types/bun": "latest"
+  },
+  "peerDependencies": {
+    "typescript": "^5.0.0"
+  },
+  "scripts": {
+    "bundle": "bun build ./grip.ts --outdir ./dist",
+    "test": "bun test"
+  }
+}

tsconfig.json

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+{
+  "compilerOptions": {
+    // Enable latest features
+    "lib": ["ESNext", "DOM"],
+    "target": "ESNext",
+    "module": "ESNext",
+    "moduleDetection": "force",
+    "jsx": "react-jsx",
+    "allowJs": true,
+
+    // Bundler mode
+    "moduleResolution": "bundler",
+    "allowImportingTsExtensions": true,
+    "verbatimModuleSyntax": true,
+    "noEmit": true,
+
+    // Best practices
+    "strict": true,
+    "skipLibCheck": true,
+    "noFallthroughCasesInSwitch": true,
+
+    // Some stricter flags (disabled by default)
+    "noUnusedLocals": false,
+    "noUnusedParameters": false,
+    "noPropertyAccessFromIndexSignature": false
+  }
+}