JavaScript prompt()

The prompt() function is a built-in JavaScript method that displays a modal dialogue box prompting the user for input. It is part of the Web API, provided by the browser’s window object, and pauses script execution until the user responds. The function returns the user’s input as a string or null if the user cancels the dialogue.

Syntax

The prompt() function accepts two parameters and returns a string or null:

prompt(message)

or, alternatively

prompt(message, defaultValue)

• message: A string that will be displayed in the dialog box.
• defaultValue (Optional): A default value pre-filled in the input field.

The function returns:

• The user’s input as a string.
• Null if the user clicks “Cancel” or closes the dialog.

Example

This example demonstrates how to use the prompt() function to get user input:

let name = prompt('Please enter your name:');

if (name !== null) {
  console.log('Hello, ' + name + '!');
} else {
  console.log("You didn't enter a name.");
}

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A greeting displaying that name appears when a name is entered and OK is clicked. If Cancel is clicked, a message indicating that no name was entered is shown.