Merge pull request #854 from caesay/patch-3

Add prop onBeforeSubmit prop to form

Author: davidkpiano

react-redux-form.d.ts

@@ -313,6 +313,11 @@ interface BaseFormProps {
      * * If you want better performance, you can use validateOn="submit", depending on your use-case.
      */
     validateOn?: 'change' | 'submit';
+    /**
+     * This handler function is called regardless of the validity of the form, and allows you to prevent the default action
+     * if using a form action url.
+     */
+    onBeforeSubmit?: (event?: Event) => void;
     /**
      * The handler function called when the form is submitted. This works almost exactly like a normal <form onSubmit={...}> handler, with a few differences:
      * * The submit event's default action is prevented by default, using event.preventDefault().