The following code can be used to retrieve a token and request the list of service locations accessible to the current account:
var test = async () => {
let formData = new URLSearchParams();
formData.append('grant_type', 'password');
formData.append('username', '{{username}}');
formData.append('password', '{{password}}');
formData.append('client_id', '{{client_id}});
formData.append('client_secret', '{{client_secret}}');
const tokens = await fetch('https://farm1pub.smappee.net/dev/v3/oauth2/token', { method: 'POST', body: formData })
.then(response => response.json());
const accessToken = tokens.access_token;
const result = await fetch('https://farm1pub.smappee.net/dev/v3/servicelocation', { headers: { Authorization: 'Bearer ' + accessToken } })
.then(response => response.json());
console.log(result);
}; test();