How to Create an Alert Box in JavaScript

Alert boxes are useful for displaying quick informational messages or warnings. They are displayed using JavaScript's alert function.

Things You'll Need

• JavaScript or text editor

Instructions

Create an Alert Box in JavaScript

1. Write the call to the alert function following the example:
   alert("Hello, World!");

2. Display the value of a variable or expression by passing it as the argument to the alert function:
   alert (my_variable);

3. Concatenate strings using the "+" operator to display multiple pieces of information in the alert box, as follows:
   alert ("You are " + age + " years old.");

Tips & Warnings

• The confirm JavaScript function closely resembles alert, but gives the user two choices, OK and Cancel, instead of just OK.