# What is ESCSS-ESTest?
A passive, non-intrusive JavaScript runtime validator designed to achieve 100% function coverage.
## Features
- ✅ `TypeScript autocompletion`.
- 🧪 Supports `E2E` & `unit testing`.
- ⚙️ Works in `Node.js` & `modern browsers`.
- ❤️🔥 Built with `security` & `developer experience` at heart.
- 🎯 `Non-intrusive` & `concise API` to achieve `100% function coverage`.
- 🔥 `Runtime dependency error detection` to eliminate `dependency hell`.
- 🪶 `2.7 kB` (minified + gzipped), `zero dependencies`, and `no vendor lock-in`.
- ⚡ (Optional) `runtime testing` with `minimal performance impact`.
## benchmark
**source**: [ESTest-benchmark-repo](https://github.com/ESCSS-labs/ESTest-benchmark-repo)
## Installation
```bash
npm add escss-estest
```
```bash
yarn add escss-estest
```
```bash
pnpm add escss-estest
```
```bash
bun add escss-estest
```
## Core Concept
**`Water filter`**
- Inspired by TDD, it's a filter for your code, making sure only clean results come through.
```js
function sum(a, b) {
// unhappy path: {...}
// Unhappy path filter. console.error (non-breaking). Collapsible. Removable.
{
ESTest(a, "number");
ESTest(b, "number");
}
// Happy path: inputs are valid
return a + b;
}
```
## Core API
### `ESTest(input, type = "null", message = globalThis.__ESCSS_ESTEST__.message)`
- Non-breaking error logging via `console.error(...)`
**case 1**
```js
import { ESTest } from "escss-estest";
function sum(a, b) {
{
ESTest(a, "number");
ESTest(b, "number");
}
return a + b;
}
```
**case 2**
```js
import { ESTest } from "escss-estest";
async function getApi(a, b) {
const apiData = await fetch("https://www.just-an-example.com/1");
const data = await apiData.json();
/**
* data = {
* name: "mike lee",
* email: "cspkno005@gmail.com"
* info: [
* {
* id: '1',
* city: 'foo',
* statusCode: 111
* },
* {
* id: '2',
* city: 'bar',
* statusCode: 222
* }
* ]
* }
*/
// Hint: Prevent undefined errors with optional chaining (?.)
{
ESTest(data.name, "string").regex(/^mike lee$/);
ESTest(data.email, "string").email();
ESTest(data.info[0]?.id, "string?");
ESTest(data.info[0]?.city, "string?");
ESTest(data.info[0]?.statusCode, "number?");
}
return data;
}
```
**image**
**source**: [mike-demo-project](https://github.com/ESCSS-labs/mike-demo-project)
### `unSafeESTest(input, type = "null", message = globalThis.__ESCSS_ESTEST__.message)`
- Breaking error throwing via `throw new Error(...)`
```js
import { ESTest, unSafeESTest } from "escss-estest";
import express from "express";
const app = express();
const port = 3000;
app.use(express.json());
app.post("/demo", (req, res) => {
try {
const data = req.body;
/**
* data = {
* name: "mike lee",
* email: "cspkno005@gmail.com"
* }
*/
{
unSafeESTest(data.name, "string", "wrong name").regex(/^mike lee$/);
unSafeESTest(data.email, "string", "invalid email").email();
}
res.json({ message: "ok" });
} catch (err) {
res.status(400).json({ message: err.message });
}
});
app.listen(port, () => {
console.log(`http://localhost:${port}`);
});
```
**image**
**source**: [mike-demo-project](https://github.com/ESCSS-labs/mike-demo-project)
### `createESTest(input, type, message)`
- Get clear, actionable `bug reports` (for library authors/maintainers).
```js
import { createESTest } from "escss-estest";
// Encapsulate createESTest to provide your library's own default message
function ESTest(
input,
type,
message = "[libraryName] your message for others to help debugging",
) {
return createESTest(input, type, message);
}
```
## Auxiliary API
### `globalThis.__ESCSS_ESTEST__.information`
- Show library information
### `globalThis.__ESCSS_ESTEST__.message`
- Captures `internal bug reports` (for company teams)
```js
// Set in the entry point, e.g., main.js, App.vue, or App.jsx...
globalThis.__ESCSS_ESTEST__.message = "Please report this issue to ...";
```
### `globalThis.__ESCSS_ESTEST__.isESTestDisabled`
- Why have this feature?
- Avoids vendor lock-in for long-term project flexibility.
- Optimizes production performance by enabling in dev and disabling in prod.
_Note: `unSafeESTest` will not be affected (for security reasons)_
```js
globalThis.__ESCSS_ESTEST__.isESTestDisabled = true;
function sum(a, b) {
{
ESTest(a, "number");
ESTest(b, "number");
}
return a + b;
}
// same as below
function sum(a, b) {
return a + b;
}
```
### `globalThis.__ESCSS_ESTEST__.analysis`
- Show usage reports
