x-www-form-urlencoded format - using https in node.js - node.js

Question

I am currently writing to an API to try and get a token. I'm nearly there but fallen at the last hurdle..
const fs = require('fs');
const https = require('https');
const ConfigParams = JSON.parse(fs.readFileSync('Config.json', 'utf8'));
const jwt = require('jsonwebtoken');
const apikey = ConfigParams.client_id;
var privateKey = fs.readFileSync(**MY KEY**);
var tkn;
const jwtOptions = {
algorithm: 'RS512',
header: { kid: 'test-1' }
}
const jwtPayload = {
iss: apikey,
sub: apikey,
aud: **API TOKEN ENDPOINT**,
jti: '1',
exp: 300
}
jwt.sign(jwtPayload,
privateKey,
jwtOptions,
(err, token) => {
console.log(err);
//console.log(token);
tkn = token;
let = tokenPayload = {
grant_type: 'client_credentials',
client_assertion_type: 'urn:ietf:params:oauth:client-assertion-type:jwt-bearer/',
client_assertion: tkn
}
tokenAuthOptions = {
payload: tokenPayload,
host: **HOST**,
path: **PATH**,
method: 'POST',
}
https.request(
tokenAuthOptions,
resp => {
var body = '';
resp.on('data', function (chunk) {
body += chunk;
});
resp.on('end', function () {
console.log(body);
console.log(resp.statusCode);
});
}
).end();
}
)
the encoded token comes back fine for the first part, the https request though returns a problem.
the response I get back is grant_type is missing, so I know I have a formatting problem due to this x-www-form-urlencoded, but I can't figure out how to fix it.
here is what the website said:
You need to include the following data in the request body in
x-www-form-urlencoded format:
grant_type = client_credentials client_assertion_type =
urn:ietf:params:oauth:client-assertion-type:jwt-bearer
client_assertion = <your signed JWT from step 4> Here's a complete
example, as a CURL command:
curl -X POST -H "content-type:application/x-www-form-urlencoded"
--data \ "grant_type=client_credentials\ &client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer
&client_assertion="
END POINT
Ideally I want a solution using the https request, but if that's not possible I'm open to other solutions.
Any help is greatly appreciated.
Thanks,
Craig
Edit - I updated my code based on a suggestion to:
const params = new url.URLSearchParams({
grant_type: 'client_credentials',
client_assertion_type: 'urn:ietf:params:oauth:client-assertion-type:jwt-bearer/',
client_assertion: tkn
});
axios.post("URL", params.toString()).then(resp => {
console.log("response was : " + resp.status);
}).catch(err => {
console.log("there was an error: " + err);
})
But I'm still getting an error code 400, but now with less detail as to why. (error code 400 has multiple message failures)

Answer 1

Postman is the best.
Thank for #Anatoly for your support which helped to point me in the right direction. I had no luck so used postman for the first time, and found it had a code snippet section, with four different ways of achieving this using node.js.
The solution with Axion was:
const axios = require('axios').default;
const qs = require('qs');
var data = qs.stringify({
'grant_type': 'client_credentials',
'client_assertion_type': 'urn:ietf:params:oauth:client-assertion-type:jwt-bearer',
'client_assertion': tkn
});
var config = {
method: 'post',
url: '',
headers: {
'Content-Type': 'application/x-www-form-urlencoded'
},
data: data
};
axios(config)
.then(function (response) {
console.log(JSON.stringify(response.status));
})
.catch(function (error) {
console.log(error);
});
I believe the issue was that I was not passing the information into 'data:' in combination with the querystring problem. Using qs.stringify to format the object, then passing this into the data: key solved the problem.