javascript - how to use require function in js

Question

I get properly credit card info upon input done I called a function to validate credit card with luhn module ( npm install luhn) as I use :

var luhn = require("luhn");
is_valid = luhn.validate(card); // should respond true.
if (!is_valid) {
            console.log("Not a valid credit card");
}
return;`

Uncaught ReferenceError: require is not defined

I am sorry If this is simple question but since I could not find a logic short solution for npm packed usage. onsubmit I call this time kkTahsil() function.

function kkTahsil() {
datalariAl();

var Iyzipay = require('iyzipay');   
var iyzipay = new window.Iyzipay({
    apiKey: 'sandbox-PZ8jicWrEeE1rt1O75FTOegr5lsW3xxx',
    secretKey: 'sandbox-2Q6aaP1FK3HFrXkTsHfftxfiudFMfxxx',
    uri: 'https://sandbox-api.iyzipay.com'
});

var nameOnCard = document.getElementById('name-on-card').value;
var expireMonth = document.getElementById('card-exp-month').value;
var expireYear = document.getElementById('card-exp-year').value;
var cvc= document.getElementById('card-cvv').value;

again same error.

so in js, there must be easy way to use npm modules. But I could not found yet. Please I need a help.

Answer 1

require is not available in the browser. It is used in Node.js.

If you want to use require on the client side then use Browserify:

Browserify lets you require('modules') in the browser by bundling up all of your dependencies.

In fact, require couldn't be available in the browser in the form as it is implemented in Node. The problem with require is that it is synchronous. It works on the server side on the first tick of the event loop when you can block on I/O because no event listeners are bound yet, but it will not work in the browser without problems because it would have to block the UI for the entire time that the modules are downloaded, compiled and run.

In fact synchronous vs asynchronous module loading has been a matter of controversy. See those answers for more details:

• Exporting Node module from promise result
• javascript - Why is there a spec for sync and async modules?