Felte's createForm function accepts a configuration object with the following properties:

• onSubmit: a function that receives as a first argument the submitted data, and as a second argument a context object with the following properties:
  • form: the native HTML form element.
  • controls: the form's native HTML controls.
  • config: the current configuration of the form.
• validate: a validation function (or array of functions) that receives the data to validate and returns an errors object, or undefined if the data is valid. The validation functions may be asynchronous. See Validation.
• warn: a validation function (or array of functions) that receives the data to validate and returns an object with the same shape as data, but with warning messages or undefined as values. It can be an array of functions whose validation errors will be merged. See Validation.
• transform: a transformation function (or array of functions) that receives the data coming from your form and returns a data object. See Transformations.
• onError: a function that receives any unhandled errors thrown in the onSubmit function. Useful for handling server errors.
• extend: an extender or array of extenders. Currently these are either validators or reporters. Note that extenders may add/change this same configuration object. Check their documentation when adding one.

Every property is optional, except onSubmit.