The DOM input event is fired synchronously when the value of an <input>, <select>, or <textarea> element is changed.
But in Chapter 5 P158, There is
"You may argue that you could implement the preceding example by handling the input event, which would be dispatched when the user finished entering the stock symbol and moved the focus out of the input field. This is true, but there are many scenarios where you’ll want an immediate response from the server, such as retrieving and filtering a data collection as the user types."
MDN input event say:
The DOM input event is fired synchronously when the value of an <input>, <select>, or <textarea> element is changed.But in Chapter 5 P158, There is
"You may argue that you could implement the preceding example by handling the input event, which would be dispatched when the user finished entering the stock symbol and moved the focus out of the input field. This is true, but there are many scenarios where you’ll want an immediate response from the server, such as retrieving and filtering a data collection as the user types."