You may need to transform your data in between it being set in your inputs and it being set in the data store. For example for handling numeric values on text inputs or transforming a value to a Date instance. Felte allows you to do this by using the transform property in createForm's configuration object. It accepts either a function or an array of functions. These functions will receive the values of the form before they're assigned to the data store, and returns a new object that will be assigned to the store. This can even allow you to change your values shape in Felte.

const { form } = createForm({
  transform: (values) => ({
    shouldBeNumber: parseInt(values.shouldBeNumber, 10),

These transformation functions run also when directly setting values to the data store (e.g. via bind:value or assigning to the data store directly).

NOTE: Transformations must be syncrhonous.