Page 51 - JavaScript

Notes

The alert method is technically a property of window object, but since all window
properties are automatically global variables, we can use alert as a global variable
instead of as a property of window - meaning you can directly use alert() instead of
window.alert().

Unlike using console.log, alert acts as a modal prompt meaning that the code calling alert will
pause until the prompt is answered. Traditionally this means that no other JavaScript code will
execute until the alert is dismissed:

alert('Pause!');
console.log('Alert was dismissed');

However the specification actually allows other event-triggered code to continue to execute even
though a modal dialog is still being shown. In such implementations, it is possible for other code to
run while the modal dialog is being shown.

More information about usage of the alert method can be found in the modals prompts topic.

The use of alerts is usually discouraged in favour of other methods that do not block users from
interacting with the page - in order to create a better user experience. Nevertheless, it can be
useful for debugging.

Starting with Chrome 46.0, window.alert() is blocked inside an <iframe> unless its sandbox
attribute has the value allow-modal.

Using window.prompt()

An easy way to get an input from a user is by using the prompt() method.

Syntax

prompt(text, [default]);

• text: The text displayed in the prompt box.
• default: A default value for the input field (optional).

Examples

var age = prompt("How old are you?");
console.log(age); // Prints the value inserted by the user

https://riptutorial.com/ 8