Add useForm hook (#111)

Co-authored-by: Gisela <gisela.difini@4all.com>
Co-authored-by: Angelos Chalaris <chalarangelo@gmail.com>

snippets/useForm.md

@@ -0,0 +1,48 @@
+---
+title: useForm
+tags: hooks,state,beginner
+firstSeen: 2021-09-17T05:00:00-04:00
+---
+
+Creates a stateful value from the fields in a form.
+
+- Use the `useState()` hook to create a state variable for the values in the form.
+- Create a function that will be called with an appropriate event by a form field and update the state variable accordingly.
+
+```jsx
+const useForm = initialValues => {
+  const [values, setValues] = React.useState(initialValues);
+
+  return [
+    values,
+    e => {
+      setValues({
+        ...values,
+        [e.target.name]: e.target.value
+      });
+    }
+  ];
+};
+```
+
+```jsx
+const Form = () => {
+  const initialState = { email: '', password: '' };
+  const [values, setValues] = useForm(initialState);
+
+  const handleSubmit = e => {
+    e.preventDefault();
+    console.log(values);
+  };
+
+  return (
+    <form onSubmit={handleSubmit}>
+      <input type="email" name="email" onChange={setValues} />
+      <input type="password" name="password" onChange={setValues} />
+      <button type="submit">Submit</button>
+    </form>
+  );
+};
+
+ReactDOM.render(<Form />, document.getElementById('root'));
+```