https://github.com/bytebodger/looks-like-email

Utility function that determines whether a string looks like a valid email address
https://github.com/bytebodger/looks-like-email

Last synced: about 1 year ago
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Utility function that determines whether a string looks like a valid email address

• Host: GitHub
• URL: https://github.com/bytebodger/looks-like-email
• Owner: bytebodger
• License: mit
• Created: 2021-02-24T14:52:37.000Z (over 5 years ago)
• Default Branch: main
• Last Pushed: 2021-03-19T03:22:52.000Z (about 5 years ago)
• Last Synced: 2025-05-19T00:17:26.719Z (about 1 year ago)
• Language: JavaScript
• Size: 97.7 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# looks-like-email

`looks-like-email` is a utility function that determines whether a string _looks_ like a valid email address.  Obviously, this function cannot tell whether a string represents a _working_ email address.  But this utility performs a series of checks to ensure that the input at least _appears_ to be a valid email address.

## Usage

After installation, import the package:

```javascript

import { looksLikeEmail } from '@toolz/looks-like-email';

```

### looksLikeEmail()

Given any string, `looksLikeEmail()` performs the following validates that:

1. The string contains exact one `@` symbol.

1. The `@` symbol does not appear the beginning or end of the string.  (The portion _before_ the `@` symbol is the "local part".  The portion _after_ it is the "domain part").

1. The local part consists of alphanumerics and/or the following characters: ! # $ % & ‘ * + - / = ? ^ _ ` . { | } ~

1. There are no consecutive periods in the local part.

1. The domain part is no longer than 255 characters.

1. There is _some kind of_ top-level domain in the domain part.  (Given the every fluctuating directory of TLDs, this utility does _not_ try to validate that the supplied TLD is a _real_ TLD.)

1. The domain part is divided into _domain labels_ by periods - and there are at least two domain labels.

1. No domain label exceeds 63 characters in length.

1. Each domain label consists of alphanumerics and/or a hyphen.

1. Domain labels do not start or end with a hyphen.

This utility uses `@toolz/string-contains` to look for alphanumerics _across the UTF-8 spectrum_. This means that letters are accepted when they are outside the ASCII range.

```javascript

const API = {

   arguments: {

      string: {

         required,

         format: string,

      },

      showWarnings: {

         optional,

         format: Boolean,

         defaultValue: false,

      },

   },

   returns: Boolean,

}

```

**Examples:**

```javascript

looksLikeEmail('adam@bytebodger@foo.com'); // FALSE

looksLikeEmail('@adambytebodger.com'); // FALSE

looksLikeEmail('abcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzy@bytebodger.com'); // FALSE

looksLikeEmail('adambytebodger.com@'); // FALSE

looksLikeEmail('ad[am@bytebodger.com'); // FALSE

looksLikeEmail('ad..am@bytebodger.com'); // FALSE

looksLikeEmail('abc@defghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzydefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzyabcdefghijklmnopqrstuvwxzybytebodger.com'); // FALSE

looksLikeEmail('adam@bytebodgercom'); // FALSE

looksLikeEmail('adam@bytebodgerbytebodgercombytebodgercombytebodgercombytebodgercombytebodgercombytebodgercombytebodgercom.com'); // FALSE

looksLikeEmail('adam@byte*bodger.com'); // FALSE

looksLikeEmail('adam@byte.-bodger.com'); // FALSE

looksLikeEmail('adam@byte-.bodger.com'); // FALSE

looksLikeEmail('adam@byte-.bodger.com', true); // FALSE (with console warning about the error)

looksLikeEmail('adam@byte.bodger.com'); // TRUE

looksLikeEmail('adam_davis1@byte.bodger.com'); TRUE

```