Node.js https.request method using client credentials - node.js

Question

I am trying to make a request for an access token using https.request but I keep getting the following error:
"error":"invalid_request","error_description":"Missing grant type"
In the Node.js HTTPS.Request documentation there isn't any reference for how to set the grant type. I believe I need to set it in the body of the request, but there is also no reference to attaching a body to the request. I am attempting to do it with the payload variable but obviously that isn't working. I am also trying to do this request with 0 or as little dependencies as possible.
function getAccessToken() {
const https = require('https')
const payload = {
"grant_type": "client_credentials"
}
const options = {
"hostname": url,
"method": "POST",
"path" : "/oauth2/token",
"port" : 443,
"encoding": "utf8",
"followRedirect": true,
"headers": {
"Authorization": "Basic <base64 encoded client_id:client_secret>",
"scope": "PARTNER_READ"
},
"payload": payload,
'muteHttpExceptions': true
}
const req = https.request(options, res => {
console.log(`statusCode: ${res.statusCode}`)
res.on('data', d => {
process.stdout.write(d)
})
})
req.on('error', error => {
console.error(error)
})
req.end()
}
Any help would be appreciated!

Answer 1

Just to close the loop on this, I was missing the 'Content-Type' in the header which I think was causing the "Missing Grant Type" error because it couldn't parse the body. I also needed to write the postData to the request right before the req.end(). So thank you #Klaycon for that point in the right direction!
Here is my updated code:
function getAccessToken() {
const querystring = require('querystring');
const https = require('https')
const postData = querystring.stringify({
'grant_type': 'client_credentials'
});
const options = {
"hostname": url,
"method": "POST",
"path" : "/oauth2/token",
"port" : 443,
"encoding": "utf8",
"followRedirect": true,
"headers": {
"Authorization": "Basic <base64 encoded client_id:client_secret>",
"Content-Type": 'application/x-www-form-urlencoded',
"Content-Length": Buffer.byteLength(postData),
},
'muteHttpExceptions': true
}
const req = https.request(options, res => {
console.log(`statusCode: ${res.statusCode}`)
res.on('data', d => {
process.stdout.write(d)
})
})
req.on('error', error => {
console.error(error)
})
req.write(postData);
req.end()
}