Postman Auth0 pre-request auth script with Collection level variables. Define collection Auth to BearerToken with {{oidc_bearer_token}}

pm.auth0.collection.pre-request

// collection pre-request script
// obtain parameters from collection configuration

const domain = pm.environment.get("auth0_domain");
const client_id = pm.environment.get("auth0_client_id");
const audience = pm.environment.get("auth0_audience");
const client_secert = pm.environment.get("auth0_client_secret");
const username = pm.environment.get("username");
const password = pm.environment.get("password");

const echoPostRequest = {
  url: domain +'/oauth/token',
  method: 'POST',
  header: {
    "Content-Type": "application/json",
  },
  body: {
    mode: 'application/json',
    raw: JSON.stringify(
        {
            username: username,
            password: password,
        	client_id: client_id,
        	client_secret: client_secert,
        	audience: audience,
        	grant_type:'password'
        })
  }
}

// Check if needed to refresh token
var getToken = true;
console.log("current oidc_bearer_token:", pm.environment.get('oidc_bearer_token'))
console.log("current oidc_bearer_token_expiry:", pm.environment.get('oidc_bearer_token_expiry'))

if (!pm.environment.get('oidc_bearer_token_expiry') || 
    !pm.environment.get('oidc_bearer_token')) {
    console.log('Token or expiry date are missing')
} else if (pm.environment.get('oidc_bearer_token_expiry') <= (new Date()).getTime()) {
    console.log('Token is expired')
} else {
    getToken = false;
    console.log('Token and expiry date are all good');
}

if (getToken) {    
    pm.sendRequest(echoPostRequest, function (err, res) {
        var responseJson = res.json();
        console.log("is resoponse error", !err, !responseJson.error, !!responseJson.access_token)
        if (!err && !responseJson.error&& !!responseJson.access_token) {
            console.log('Setting the token and expiry date',responseJson.access_token, responseJson.expires_in )
            
            // save results to environment configuration
            pm.environment.set('oidc_bearer_token', responseJson.access_token)

            var expiryDate = new Date();
            expiryDate.setSeconds(expiryDate.getSeconds() + responseJson.expires_in);
            pm.environment.set('oidc_bearer_token_expiry', expiryDate.getTime());
        }
        else {
            console.log({err});
            console.error('Error: ' + {responseJson})
        }
    });
}