Fix handleSubmit typings (#715)

Author: forivall

src/ReactFinalForm.js

@@ -13,7 +13,7 @@ import type {
   FormValuesShape,
   Unsubscribe
 } from 'final-form'
-import type { FormProps as Props } from './types'
+import type { FormProps as Props, SubmitEvent } from './types'
 import renderComponent from './renderComponent'
 import useWhenValueChanges from './useWhenValueChanges'
 import useConstant from './useConstant'
@@ -163,7 +163,7 @@ function ReactFinalForm<FormValues: FormValuesShape>({
     form.setConfig('validateOnBlur', validateOnBlur)
   })
 
-  const handleSubmit = (event: ?SyntheticEvent<HTMLFormElement>) => {
+  const handleSubmit = (event: ?SubmitEvent) => {
     if (event) {
       // sometimes not true, e.g. React Native
       if (typeof event.preventDefault === 'function') {

src/types.js.flow

@@ -51,8 +51,16 @@ export type FieldRenderProps = {
   }
 }
 
+export type SubmitEvent = {
+  preventDefault?: $PropertyType<SyntheticEvent<EventTarget>, 'preventDefault'>,
+  stopPropagation?: $PropertyType<
+    SyntheticEvent<EventTarget>,
+    'stopPropagation'
+  >
+}
+
 export type FormRenderProps<FormValues: FormValuesShape> = {
-  handleSubmit: (?SyntheticEvent<HTMLFormElement>) => ?Promise<?Object>,
+  handleSubmit: (?SubmitEvent) => ?Promise<?Object>,
   form: FormApi<FormValues>
 } & FormState<FormValues>
 

typescript/index.d.ts

@@ -53,7 +53,9 @@ export interface FormRenderProps<FormValues = AnyObject>
     RenderableProps<FormRenderProps<FormValues>> {
   form: FormApi<FormValues>;
   handleSubmit: (
-    event?: React.SyntheticEvent<HTMLFormElement>
+    event?: Partial<
+      Pick<React.SyntheticEvent, 'preventDefault' | 'stopPropagation'>
+    >
   ) => Promise<AnyObject | undefined> | undefined;
 }