A validation module for browsers and Node.js to validate credit card numbers against the luhn algorithm.
npm install luhnnode-luhn 
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A JavaScript module of the luhn algorithm for Credit Card Validation that works with both client-side JavaScript and Node.js
npm install luhn
The luhn module has unit tests built around it than can be used to verify the package before usage. The tests are written with the Mocha and Should modules and running the below command will import such.
npm test luhn
Once the package has been installed using npm, using the module is very simple. At the moment, the module includes an luhn object that exposes a single method, validate. validate accepts a single string parameter that represents the credit card number.
#### Node.js ####
``javascript`
var luhn = require("luhn");
var is_valid = luhn.validate("4111111111111111"); // should respond true.
Luhn 1.0.8 provides a more globally accessible way of using Luhn outside of Browserify. The algorithm is the same as of v2.0; however, the client-side instructions are different and provided with that version.
#### Html ####
`html`
#### JavaScript ####
`javascript`
var luhn = luhn;
var is_valid = luhn.validate("4111111111111111"); // should respond true.
By default, the luhn module places itself into the global scope in the browser. If you would prefer to NOT have it be directly attached to the window object, you can add your own namespace` at the top of the luhn.js file.
Copyright (c) 2020 James Eggers
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.