fitfab / isEmail

isEmail

It's a project setup as sample on how to work with TypeScript and Jest -- it contains a simple method that checks for a valid email.

It is also deployed to NPM as to demostrate the deployment process.

You will need to have nodejs and an updated version of npm.

To update to the latest NPM version run this command: npm i -g npm

1 Create a repo in github.com

• add .gitignore: Node
• add a license: MIT License

Once you created the empty repo clone it:

$git clone https://github.com/<new-repo-nane>.git

$cd <new-repo-name>

2 Initialize the project

$$ npm init

3 Install TypeScript

npm i -D typescript

• add the tsconfig.json file

{
 "compilerOptions": {
   "target": "es5",        /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', or 'ESNEXT'. */
   "module": "commonjs",   /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
   "declaration": true,    /* Generates corresponding '.d.ts' file. */
   "outDir": "./dist",     /* Redirect output structure to the directory. */
   "strict": true          /* Enable all strict type-checking options. */
 }
}

• update the package.json file

  "scripts": {
   "build": "tsc"
 }

4 Install Jest

This setup should allow you to write Jest tests in Typescript and be able to locate errors.

npm i -D jest ts-jest @types/jest

• update the package.json

   "scripts": {
   "build": "tsc",
   "test": "jest",
   "test:watch": "jest --watch",
   "coverage": "jest --coverage"
 }
  "jest": {
   "transform": {
     "^.+\\.tsx?$": "ts-jest"
   },
   "testRegex": "(/__tests__/.*|(\\.|/)(test|spec))\\.(jsx?|tsx?)$",
   "moduleFileExtensions": [
     "ts",
     "tsx",
     "js",
     "jsx",
     "json",
     "node"
   ]
 }

5 create the source and test file

At this point create a /lib folder and the index.ts file:

export default function isEmail(str:string):boolean {
    // Verify : https://regex101.com/r/VBGyXV/1
    const re = /^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,6}$/
    return re.test(str)

}

and the test file:

import isEmail from './index'

describe('Email Utility', ()=> {
    test('checks for a valid email', ()=> {
        expect(isEmail('[e-mail]')).toBe(true)
    })
    test('recognizes a malformed email', ()=>{
        expect(isEmail('me@mail')).toBe(false)
    })
})

Setup to Publish to NPM