How do you make this curl request in node - node.js

Question

This curl request to the spotify API works perfectly fine
curl -X "POST" -H "Authorization: Basic <my-key-here>" -d grant_type=client_credentials https://accounts.spotify.com/api/token
I'm trying to do this in node, but it's not working and returns a 400 Bad Request. Here is my code. What am I doing wrong?
function AuthRequest(key) {
const req_body_params = JSON.stringify({
grant_type: "client_credentials"
})
const base64_enc = new Buffer(key).toString("base64")
const options = {
host: "accounts.spotify.com",
port: 443,
path: "api/token",
method: "POST",
headers: {
"Content-Type": "application/json",
"Authorization": `Basic ${base64_enc}`
}
}
const req = https.request(options, function (res) {
res.on('data', function (data) {
alert("success: " + data)
})
})
req.on('error', function (err) {
alert("error: " + err)
})
req.write(req_body_params)
req.end()
}
I'm trying to use the Client Credentials method as explained here: https://developer.spotify.com/web-api/authorization-guide/

Answer 1

The request should be in application/x-www-form-urlencoded instead of JSON, it should be const req_body_params = "grant_type=client_credentials" with a header of "Content-Type": "application/x-www-form-urlencoded"
function AuthRequest(key) {
const req_body_params = "grant_type=client_credentials";
const base64_enc = new Buffer(key).toString("base64");
const options = {
host: "accounts.spotify.com",
port: 443,
path: "/api/token",
method: "POST",
headers: {
"Content-Type": "application/x-www-form-urlencoded",
"Authorization": `Basic ${base64_enc}`
}
};
const req = https.request(options, function(res) {
res.on('data', function(data) {
alert("success: " + data)
})
});
req.on('error', function(err) {
alert("error: " + err)
});
req.write(req_body_params);
req.end();
}

Answer 2

Because token expires is good to request them dynamically, I created a method that output a token as a promise, then you can consume in your request.
const axios = require('axios')
const client_id = process.env.SPOTIFY_CLIENT_ID;
const client_secret = process.env.SPOTIFY_CLIENT_SECRET;
function getToken( ) {
return axios({
url: 'https://accounts.spotify.com/api/token',
method: 'post',
params: {
grant_type: 'client_credentials'
},
headers: {
'Content-Type': 'application/x-www-form-urlencoded'
},
auth: {
username: client_id,
password: client_secret
}
})
}
async function getSpotifyData( endpoint ){
const tokenData = await getToken( );
const token = tokenData.data.access_token;
axios({
url: `https://api.spotify.com/v1/${endpoint}`,
method: 'get',
headers: {
'Authorization': 'Bearer ' + token
}
}).then( response => {
console.log( response.data );
return response.data;
}).catch( error => {
throw new Error(error);
});
}
getSpotifyData( 'browse/new-releases' );