Postman pre-request script to generate a signature string for spatie/laravel-webhook-client

script.js

// Do this:
// - Set a `webhook_secret` variable that what you've set on the webhook server.

// This generates a signature string from the header 
var signatureString = CryptoJS.HmacSHA256(request.data, pm.environment.get('webhook_secret')).toString();

// This dynamically generates the {{signature}} variable. Create a Signature header with {{signature}} as the value.
pm.environment.set('signature', signatureString);