create an invoice stripe using google app script - google-apps-script

Question

Hi I followed this documentation regarding on creating an invoice on stripe
it says here that The ID of the customer who will be billed.
so I created a test customer manually on stripe and now I tried this code
function testDataInvoices()
{
var url = "https://api.stripe.com/v1/invoices";
var params = {
method: "post",
headers: {Authorization: "Basic " + Utilities.base64Encode("sk_testXXXXX:")},
payload:
{
customer: "cus_JLKM93Pc6j2mxB",
}
};
var res = UrlFetchApp.fetch(url, params);
Logger.log(res.getContentText())
}
but I am getting this error
Exception: Request failed for https://api.stripe.com returned code 400. Truncated server response: {
"error": {
"code": "invoice_no_customer_line_items",
Can someone please enlighten me about this stripe I really just new to this API and their API is just only for node.js
#TRIED
I tried following this link
and change my code to this
function testDataInvoices()
{
var url = "https://api.stripe.com/v1/invoices";
var params = {
method: "post",
headers: {Authorization: "Basic " + Utilities.base64Encode("sk_test_XXXXXX:")},
payload:
{
"email": "paul.kevin#senren.page",
"payment_settings": 'pm_1FWS6ZClCIKljWvsVCvkdyWg',
"invoice_settings[default_payment_method]":'pm_1FWS6ZClCIKljWvsVCvkdyWg'
}
};
var res = UrlFetchApp.fetch(url, params);
Logger.log(res.getContentText())
}
and got this error

Answer 1

A few things:
I'm not familiar with Google App Scripts — are you sure it's safe to store a secret key in such a script and you don't need an actual backend server instead? That key has to be kept private since it can be used to do anything on your Stripe account.
In the first case, you get an error because to issue an Invoice, you have to first call /v1/invoiceitems to add some items to the customer. Then when you call /v1/invoices, which will pull those in to charge for them: https://stripe.com/docs/invoicing/integration#create-invoice-code
in the second case you get an error because those are not valid parameters for that endpoint(if you check the link you posted, those parameters are for /v1/customers, not /v1/invoices).
I'd suggest following https://stripe.com/docs/invoicing/integration .